GBCSA_Guidelines.pdf

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Acknowledgements

The ollowing people contributed to the development o the guide: Enoch Liphoto, Richard Holden,Linda Phalatse, Linda Manyuchi, Jeremy Gibberd and Liteboho Mphutlane.

Contact

It is likely that this document is updated and improved over time. Should you have any suggestionsplease email suggestions to Linda Manyuchi at [email protected].

Disclaimer

The views and opinions expressed in this publication are those o the authors and do not necessarilyrefect those o the City o Joburg.

While reasonable eorts have been made to ensure that the contents o this guide are actually correct,the City o Joburg does not accept responsibility or the accuracy or completeness o the contents, andshall not be liable or any loss or damage that may result, directly, or indirectly, through the use o, or

reliance on, the contents o this publication.

City o Joburg, Gauge, CSIR 2008This work is copyright and no part may be reproduced without written permission. Permission orreproduction should be directed to the City o Joburg.


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Table o contents

1. Introduction 6

1.1 Who is the guide aimed at? 71.2 What does the guide cover? 71.3 Limitations o the guidelines 71.4 Structure o the guidelines 8

2. Why have a guide on energy eciency in buildings? 10

2.1 Global warming 102.2 Reduced ongoing costs 122.3 Compliance with tightening legislation and standards 122.4 Limiting the requirement or additional power 132.5 Market and client demands 13

3. Design processes or energy eciency 14

3.1 The role o design 153.2 Integrated design processes 153.3 Stage one: Appraisal and denition o the project 163.4 Stage two: Design concept 163.5 Stage three: Design development 163.6 Stage our: Technical documentation 173.7 Stage ve: Contract administration and inspection 173.8 Compliance with SANS 204 17

4. Human comort and minimum environmental standards 18

4.1 Occupational Health and Saety (OSH) Act and Regulations 194.2 Thermal comort 194.3 Daylight 204.4 Ventilation 204.5 Local control 20

5. Climate 21

5.1 Location 225.2 Temperature, humidity and rainall 225.3 Solar radiation 225.4 Solar charts 23

6. Environment control strategies in buildings 24

6.1 Choice o environment control strategy 256.2 Active environmental control strategies 266.3 Selecting active environmental control strategies 276.4 Passive environmental control strategies 276.5 Selecting passive environmental control strategies 28

7. Site 29

7.1 Location 307.2 Existing buildings 307.3 Browneld sites 30

7.4 Building orientation 307.5 Access to light 317.6 Access to sunlight 31


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7.7 Access to ventilation 317.8 Noise 317.9 External hard surace and car parking 317.10 Cycling and walking 327.11 Comortable outside spaces 32

7.12 Access to acilities 327.13 Neighboring sites 32

8. Building orm and envelope 33

8.1 Surace area to volume ratio 348.2 Direct solar gain 348.3 Indirect solar gain 348.4 Cross ventilation 358.5 Stack eect system 358.6 Nighttime cooling 358.7 Day lighting 368.8 Shading devices 368.9 Colour 37

8.10 Insulation 388.11 Glazing in aades 388.12 Windows 388.13 Glass 398.14 Doors 39

9. Internal space 40

9.1 Functions 419.2 Ventilation 419.3 Thermal mass 419.4 Internal walls 429.5 Finishes 42

10. Mechanical systems 43

10.1 Zoning 4410.2 Pre-heating and pre-cooling 4410.3 Natural or economy cycle 4510.4 Mechanical ventilation 4510.5 Exhaust ans 4510.6 Vertical transportation 45

11. Electrical lighting 46

11.1 Lamp selection 47

11.2 Zoning and circuits 4811.3 Lighting maintenance 4811.4 Lighting control 4811.5 Energy consumption 48

12. Water heating 50

12.1 Solar water heating 5112.2 Pipe runs 5112.3 Insulation 5112.4 Hot water temperature 5112.5 Hot water consumption 5212.6 Hot water energy targets 52


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13. Appliances and equipment 53

13.1 Ratings and controls 5413.2 Domestic appliances and equipment 5413.3 Oce equipment 54

14. Integrated control systems and monitoring 55

14.1 Meters 5614.2 Sub-metering 5614.3 Switching and controls 5614.4 Thermostats 5614.5 Daylight sensors 5614.6 Movement sensors 5614.7 Timers 5714.8 Building management systems 57

15. Useul checklists and inormation 58

15.1 Oce design checklist 59

15.2 Residential design checklist 61

15.3 Benchmarks 63

15.3.1 Articial lightning 6315.3.2 Maximum energy demand 6415.3.3 Maximum energy consumption in buildings with articial environment

control 6415.3.4 Notional energy usage intensity requirements or buildings with natural

environmental control requirements or buildings 65

15.4 Solar chart or latitude 2600 south 66

15.5 Acronyms 67

15.6 Denitions 68

15.7 Useul links 70

15.8 Reerences 71


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Section 1Introduction


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1 Introduction

This guide has been developed to support the development o energy ecient buildings within theCity o Johannesburg. It provides practical guidance on ways o designing buildings that minimize the

requirement or energy and has been developed by the City as part o a strategy to reduce energyconsumption and address global warming within the municipality.

1.1 Who is the guide aimed at?

The guide is aimed at Architects, Designers, Planners and Developers who wish to develop more energyecient buildings. It can be used in the ollowing ways:

Design teams can use the guidelines to develop and check their designs in order to maximise theuse o opportunities or energy eciency.

Building developers and owners can use the guide as part o a design teams design brie. They canuse it to structure discussions that ensure challenging energy eciency targets are set and achievedin new buildings.

Planners and urban designers can use the guide as an input into developing more energy ecientsettlements and cities.

1.2 What does the guide cover?

The guide has a ocus on design or energy eciency and thereore emphasis strategies that minimizeenergy consumption through integrated design processes. There is a strong emphasis on passiveenvironmental control, day lighting and the use o renewable energy such as solar power. It does notdetail how to make mechanical systems, such as air conditioning and vertical transportation plant,energy ecient.

The document aims to provide guidance that is relevant to both oce buildings and residentialbuildings, and a range o buildings in between. This scope limits the extent to which dierent buildings

types can be dealt with in detail. Design teams should develop building-type and site-specic responsesthat address and work with the local context.

The guidelines ocus on the design o buildings and have been developed or use in the early designstages o a new building. While the guidelines mainly address energy use in building operation theyalso include aspects where buildings can contribute to energy eciency in the wider context, throughor instance, reducing vehicular use. The scope o the guide is limited to buildings and their immediatesurroundings and energy eciency at a wider urban, or city scale, is not addressed.

1.3 Limitations o the guidelines

The guide provides practical guidelines and rules-o-thumb that have been developed throughinternational and local research. It should be noted that the guidelines do not apply to all conditions

and are not a substitute or proper calculations and modeling by the design team.

The guidelines do not address other aspects required in sustainable buildings such as waterconsumption and waste management.

They also do not replace statutory requirements or buildings. All relevant regulations, standards andbylaws should be consulted and complied with.


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1.4 Structure o the guidelines

The guidelines have the ollowing sections:

Section ContentWhy have a guide on energy eciency inbuildings?

Key reasons or addressing energy in buildings

Design processes or energy eciency:

Actions that can be carried out by the mainrole-players at dierent stages o a buildingslie cycle to ensure that energy eciency isaddressed

Human comort and minimum environmentalstandards:

Key environmental conditions required orhealth and comort o building occupants

Environmental control strategies in buildings:

Broad strategies that can be used to support

energy ecient environmental control obuildings

SiteHow the layout o a site can be used tosupport energy eciency

Building orm and envelope

Building orm and building envelope infuenceenergy consumption and this section outlineshow strategies such as passive environmentalcontrol and day lighting can be used to reduceenergy consumption

Internal space

Internal spatial layouts can be conguredto support energy eciencies. This section

outlines some the key considerations thatshould be taken into account

Mechanical systemsAspects o how mechanical systems inbuildings can be made more ecient

Electrical lightingHow energy eciency can be addressed inelectrical lighting systems

Water heatingOutline o additional energy ecient waterheating systems including solar water heaters

Appliances and equipmentGuidance on minimising the energyconsumption by appliances and equipment inbuildings such as computers

Integrated control systems and monitoring:Control and monitoring systems to supportenergy eciency


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2 Why have a guide on energy eciency inbuildings?

There are many pressing reasons why all new buildings should be designed to be energy ecient.These include:

Global warmingReducing operating costsCompliance with tightening legislation and standards Limiting the requirement or additional powerMarket and client demands

2.1 Global warming

Increasing carbon emissions and a reduction in the ability o the natural environment to absorb carbondioxide is leading to an accumulation o greenhouse gases in the upper atmosphere. These gases

trap more heat in the upper atmosphere leading to global warming and temperatures are predictedto increase by 2 - 6OC by the end o the century (IPCC, 2007). Estimates carried out or the City oJoburg indicate that temperatures in the short term may increase between 2 and 3.5C (Hewitson,Engelbrecht, Tadross, Jack, 2005).

South Arica produces the highest CO2 emissions in Arica and has one o the highest CO2 emissionsper GDP in the world (Van Mierlo, 2007), as indicated in the graph below.

Figure 1. GDP and kW per capita

There is a direct link between buildings, carbon emissions and the ability o the natural environment toabsorb carbon dioxide. Globally, 40% o energy use, 17% o resh water use, 25% o wood harvestedand 40% o material use is attributed to the built environment (USGBC 2008). Buildings are also otenbuilt on green eld sites urther reducing the capacity o the natural environment to absorb carbondioxide.

Energy is consumed throughout the liecycle o buildings. This includes the construction, operation and

demolition o buildings. The approximate proportions o energy consumption at the dierent liecyclestages are shown below.


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Figure 2. Liecycle energy use in buildings

Energy in buildings is required to provide lighting, heating and cooling, hot water and to power

equipment and appliances. This varies between buildings, however the approximate proportions oenergy used in a conventional Johannesburg oce and residential building are shown below.

Figure 3. Energy consumption in large air-conditioned oce building

Figure 4. Energy consumption in a medium sized house


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2.2 Reduced ongoing costs

More energy ecient buildings benet their owners and tenants by having lower energy bills. Whileelectricity costs in South Arica have been some o the lowest in the world, costs will increase rapidlyand Eskom taris are set to double in the next 5 years. Interventions at Megawatt Park, a large oce

building owned by Eskom, demonstrate how energy costs can be substantially reduced or relativelylow capital expenditure. In addition substantial environmental impacts can also be achieved, asindicated below.

Energy

eciency

measures

Capital

cost

Reduced

energy cost

per year

Payback

period

Environmental

impacts

Lighting upgradeInstallation ovariable speeddrives

R4.5 million R2.2 million 25 months

Reduced C02,

SOx and NOxemissions,43,000m3 owater saved

Table 1. Energy eciency measures and impacts in a large commercial building

Simple measures can also be taken to reduce energy consumption in a residential setting. For instance,more ecient lighting, a hot box and a solar water heating substantially reduce energy costs. Thecapital costs o these technologies can be justied through reduced annual energy costs, as indicatedbelow.

Energy eciency

measureCapital cost

Reduced energy

cost per yearPayback period

Compact fuorescentlight bulb (Eskom2008)

R12 more than

tungsten bulbR18 saving per year 10 months

Hot box (Insulatedcontainer used tocomplete cookingonce initial heating oood is complete)

R120 R163 per year 9 months

Solar water heaterR5,000 R10,000more than aconventional geyser

R1,000 R1,750 peryear

5 years

Table 2. Energy eciency measures and impacts in a residential building

2.3 Compliance with tightening legislation and standards

Increasingly, legislation in South Arica will require more energy ecient buildings. The South AricanBureau o Standards (SABS) is developing new standards on energy eciency and municipalities suchas the City o Joburg and the City o Tshwane are investigating the development o by-laws andincentives schemes to reduce energy consumption in buildings. Policies and standards supportingenergy eciency in buildings include:

Energy Eciency Strategy (Department o Minerals and Energy)White Paper on Renewable Energy (Department o Minerals and Energy) SANS 204-2, Energy eciency in buildings with articial or natural environmental control Part 2

Application o energy eciency provisions in buildings with natural environmental control SANS 204-3, Energy eciency in buildings with articial or natural environmental control Part 3

Application o energy eciency provisions in buildings with articial environmental control SANS 204-4, Energy eciency in buildings with articial or natural environmental control Part 4

Application o energy eciency provisions in Category 1 houses SANS 1307, Domestic solar water heaters


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2.4 Limiting the requirement or additional power

Eskom has been unable to develop its generating capacity at the same rate at which developmenthas occurred in South Arica. This will lead to load shedding and power cuts until at least 2014. Moreenergy ecient buildings will help reducing the number o power cuts that occur.

Eskom, the Department o Mineral and Energy and Central Energy Fund are also developing a range oincentives to reduce peak power consumption and support energy eciency. These include subsidies

o up to 100% or energy ecient lighting and solar water heating. More inormation on theseschemes can be obtained rom www.eskom.co.za, www.dme.gov.za and www.ce.co.za

2.5 Market and client demands

Clients and the market are demanding more energy ecient buildings. This refects a concern aboutthe environment and a wish to achieve environmental standards required in schemes such as theGlobal Reporting Initiative (GRI). The GRI requires reporting on the ollowing indicators that are directlyrelated to energy eciency.

EN3 Direct energy consumption broken down by primary energy source EN4 Indirect energy consumption broken down by primary energy source EN5 Percentage o total energy consumption met by renewable sources EN6 Total energy saved due to conservation and eciency improvements EN7 Initiatives to provide energy-ecient products and services EN8 Initiatives to reduce indirect energy consumption. EN17 Greenhouse gas emissions EN18 Emissions o ozone-depleting substances EN19 NOx, SOx, and other signicant air emissions by weight

A recent study in the USA indicates that properties that achieved the US Energy Star rating sold or 27per cent more than buildings that had ailed to achieve the rating. Occupancy levels in these buildingswere also ound to be 92 per cent compared the 87 per cent or less energy ecient buildings. (FM

World, 2008)


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Section 3Design processes or energy eciency


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3 Design processes or energy eciency

3.1 The role o design

Energy should be addressed as soon as possible in the design process. Ideally, this is a concern at theoutset and inorms all aspects o the building including the choice o site, the size o the building anddetailed design o the building envelope, systems and interior. An integrated approach during designdevelopment stages and contract administration can be used to support energy eciency and isdescribed below. This helps to ensure that strategic decisions are correct and opportunities are takento maximise energy eciency. I early strategic decisions are wrong, the potential energy savings arereduced and the degree o eort required to achieve energy savings are much higher, as indicated inthe diagram below.

Stage 1 appraisal

& denition

Stage 2 design

concept

Stage 3 design

development

Stage 4 technical

documentation

Stage 5 contract

administration &

inspection

Table 3. Energy savings and the design process

3.2 Integrated design processes

An integrated design process can be used to help ensure that energy ecient buildings are achieved.Aspects o this approach include:

Knowing your building type: The design team ensures that they understand how energy is usedin the building type proposed. This includes studies o existing and energy ecient buildings tounderstand how, and where, energy is used. These studies provide useul targets and approachesthat can be built on.

Explicit targets: Early in the design process, challenging energy eciency targets based on

studies above, are set or the building and agreed on by the design team and the client. Checksare made to ensure that targets exceed good practice benchmarks and energy eciency standards,such as SANS 204.

Integrated design: Concept design development is carried out jointly by the design team toensure that high perormance, integrated solutions are developed.

Specialists: Where appropriate, specialist input is sought and used to inorm the design. Examplesinclude the use o passive environmental control and modelling expertise to develop low energy,passive solutions, aade engineers and glass specialists to optimize building envelope designs orenergy eciency and specialist urban designers and landscape architects to develop site layoutsand built orm that support energy eciency.

Responsive design: The approach ensures that the design o the building responds to, and workswith, eatures o a site and local climate. Thus the design may respond to topography and existingvegetation to achieve optimum access to natural ventilation and light. This requires a detailedanalysis o the site.

Modeling and an iterative design process: Having set explicit and challenging targets, thedesign team make sure that these are achieved, or exceeded, through calculations and modeling.Dierent options are explored and modeled to identiy the best approach and in an iterative way,high perormance integrated solutions are developed.


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3.3 Stage one: Appraisal and denition o the project

Activity By

Check whether a new building is really required. Using, and

improving, an existing building avoids demolition waste andenergy required or new construction.

Client

Select a design team with low energy building experience andskills. Ideally, ensure that they have worked together and ollowand integrated design process (see above).

Client

Provide a brie to the design team which outlines key energytargets and request that this is developed urther to ensure thattargets are both detailed and challenging.

Client

Undertake background studies on energy consumption patternso the proposed users o the building and or the building type.Establish key actors that will impact energy consumption withinand around the proposed building including work patterns,

environmental conditions and transportation patterns o bothpeople and goods.Discuss strategic options or reducing energy consumptionincluding site locations near public transport or residential areas,home working building management techniques such as hot-desking and the sharing o acilities with other local buildings.

Design team and client

Develop detailed energy targets or the building and outline theimplications o pursuing these to the client. Implications couldinclude urban site location, reduce building size, more fexiblethermal conditions and a requirement or specialist consultantsand modelling.

Design team

Undertake easibility studies and analysis to identiy sites and or

buildings that will achieve energy targets.Design team

3.4 Stage two: Design concept

Activity By

Analyse environmental aspects o the site in order to understandhow building design can work with these to reduce energyconsumption.

Design team

Develop concept designs that aim to achieve energy targets. Design team

Check, through modelling and calculations, that the proposedapproach will achieve targets. Report on progress.

Design team

Check that targets are being achieved. Client/independent adviser

3.5 Stage three: Design development

Activity By

Develop detailed designs that aim to achieve energy targets. Design team

Check, through modelling and calculations, that the proposedapproach will achieve targets. Report on progress.

Design team

Check that targets are being achieved. Client/independent adviser


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3.6 Stage our: Technical documentation

Activity By

Develop detailed designs that will achieve energy targets. Ensure

that tender and contractual documentation requires contractorand relevant suppliers to contribute, as required, in order toachieve energy targets.

Design team

Check, through modelling, calculations and inspections thatenergy targets are being achieved. Report on progress.

Design team

Conrm that energy targets are being achieved. Client/independent adviser

3.7 Stage ve: Contract administration and inspection

Activity By

Ensure that the completed building achieves energy targets. Putin place systems that enable close control and monitoring oenergy consumption in the building. Issue manuals and technicalinormation that detail the energy targets and explain how thebuilding should be operated to maximise energy eciency to thebuilding operator or acilities management. Report on progress.

Design team

Provide acilities management training using inormationdeveloped by design team above to ensure that there is strongcapacity and systems to support energy ecient operation o thebuilding.

Design team/Facilitiesmanagement

Develop induction training or new occupants o the building toensure that they understand the buildings systems and will usethese to achieve maximum energy eciency in the building.

Facilities management/Human resources

Carry out a Post Occupancy Evaluation to conrm that building,systems, management and occupants are working togetherto achieve required energy targets. I necessary, take actionto address problems and ensure integrated and ecientperormance.

Client/independent adviser

3.8 Compliance with SANS 204

Energy eciency can be demonstrated through compliance with SANS 204, a South Arican Bureau oStandards (SABS) standard on energy eciency in buildings. A rational design prepared by a competentperson can be used demonstrate that the design will not exceed the maximum energy demand and themaximum annual consumption gures provided in SANS 204-1. Alternatively, compliance with SANS

204-2, SANS 204-3 or SANS 204-4 can be demonstrated.


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Section 4Human comort and minimum environmental

standards


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4 Human comort and minimum environmentalstandards

There is a strong correlation between environmental conditions including temperature, humidity,

daylight and ventilation, and human health and productivity. In achieving energy eciency, it isimportant not to provide unhealthy or unsae environments. Environments should always comply withminimum standards required by legislation such as the Occupational Health and Saety Act. Designersshould also understand the key variables that aect health, comort and productivity in order tounderstand how these can be used in strategies to develop energy ecient buildings.

4.1 Occupational Health and Saety (OSH) Act and Regulations

The OSH Act provides minimum standards that must be complied with in buildings. The Act isupdated, so designers should ensure that they reer to the latest version. The 2007 version has theollowing requirements that are relevant to buildings and energy:

At least 0.3 lux is required at foor level in workplaces where there is no natural light or where

people habitually work at night to enable employees to evacuate saely.Where employees work the majority o their shit in rooms o less than 100m2, the total glazed

area o the room shall be three ths o the square root o the area o the room. Windows sillsshould not be higher and window heads not lower than one and hal metres above foor level.Windows must be glazed in a transparent material.

Minimum average values o maintained illuminance, measured on the working plan, are set out inthe Act. These speciy 300lux or general oces, 200lux or classrooms and 75lux or passages andlobbies (at foor level).

4.2 Thermal comort

Thermal comort is determined by the ollowing variables:

Activity: Activity is measured in mets, which equates to watts per square meter o body surace.This ranges rom rom 0.7 met or sleeping to 7.0 met or competitive wrestling.Clothing: Clothing provides insulation and is measured in clos. Clothing perormance range rom a

measure o 1.5 clo or a heavy business suit to 0.1 clo or a pair o shorts.Air temperature: Air temperature is usually measured as the average air temperature in the

occupied areas. People usually eel comortable where temperatures are within a range o between18 to 26oC.

Radiant temperature: The radiant temperature o the surrounding suraces also has an eecton human comort. Diering surace temperatures, or instance when the temperature o a largewindow is much cooler than other suraces in a room, can lead to discomort as a result o radiantasymmetry.

Air movement: Air movement aects heat loss rom a body and moving air can be used to cooland increase comort at higher temperatures.

Humidity: Humidity at high temperatures has a negative eect on comort and continuous levels

o high humidity can result in mould and mites in buildings.

These variables can be used to as part o environmental control strategies that achieve occupantcomort in highly energy ecient ways. Some examples are provided below:

Clothing: Encouraging people to wear light, loose-tting clothing enable people to experiencehigher temperatures without discomort. Similarly, encouraging people to wear warm clothes inwinter enables them to experience cooler temperatures without discomort.

Air movement: Using windows and ceiling ans to direct air movement around people creates acooling eect that enables higher temperatures to be experienced without discomort.

Radiant temperature: Insulation in a building can increase mean radiant temperatures, enablinglower air temperatures to be experienced without discomort.


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Section 5Climate


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5 Climate

A good understanding o climate enables designers to develop buildings that respond and work withthis to create comortable, energy ecient, environments. Climatic inormation or South Arican canbe accessed rom www.weathersa.co.za. Key aspects o Johannesburg climate are outlined below. Itshould be noted that within a city as large as Johannesburg climate will vary. It is thereore importantto get climatic data or the site being developed, or as near as possible to this.

5.1 Location

Johannesburg has the ollowing latitude, longitude and altitude:

Latitude: 26 08 SLongitude: 28 14 EAltitude: 1694m above sea level

5.2 Temperature, humidity and rainall

Temperatures, humidity and rainall or Johannesburg are outlined in the table below.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ave

Maximummonthlytemperature(oC)

25.6 25.1 14.7 21.2 18.9 16 16.6 19.3 22.8 23.7 24.1 25.2 21.1

Minimummonthlytemperature(oC)

14.7 14.2 13.2 10.4 7.3 4.2 4.3 6.3 9.5 11.3 12.7 13.9 10.17

Averagemonthlyamplitude(K)

10.9 10.9 1.5 10.8 11.6 11.8 12.3 13.0 13.3 12.4 11.4 11.3 10.93

Averagemonthlyrelativehumidity(%)

64.0 65 64 61.5 53.5 51.5 48.5 46.0 46.0 52.5 59.5 60.5 56.04

Averagemonthlyrainall mm

126 90 91 52 13 8 4 6 28 73 118 105 59

Table 4. Temperature, humidity and rainall in Johannesburg

5.3 Solar radiation

Solar radiation levels in South Arica are amongst the highest in the world. Average daily solar radiationvaries between 4.5 and 7 kWh/m2. Even in winter, parts o the country receive more than 6.5 kWh/m2per day (Banks D. and Schafer J. 2006).

The duration o sunshine is also high. Johannesburg receives bright sunshine or periods equivalento between 70% (summer) and 80% (winter) o possible duration. This compares to London (33%),Sidney (49%) and Haia (73%). These gures indicate that Johannesburg has excellent and reliablesolar energy. This ree resource can be used in passive environmental control strategies, solar water

heaters and photovoltaic systems to improve energy eciency in buildings.


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5.4 Solar charts

The location o the sun in the sky or any given time can be easily ascertained using a solar chart. Thesolar chart at the end o the document shows how the azimuth (position relative to North) and thealtitude (height) o the sun in the sky or a particular day (22 Dec) and time (4.00PM) can be read o

the chart (Azimuth 101o

in the South West SW, Altitude 35o

).

A guide, Solar Charts or the Design o Sunlight and Shade in buildings in South Arica, is availablerom the CSIR that provides more detail on solar calculations. Sotware and some computer aideddesign (CAD) packages can also be used or sunlight and shadow projections.


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6 Environmental control strategies in buildings

A key unction o buildings is to regulate the internal environment to ensure that it is comortable andhealthy or human beings. There are three main approaches to environment control. Each o these has

dierent energy implications and is outlined below:

Active environmental control: This approach is characterized by the use o mechanical heating,ventilation and air conditioning (HVAC) systems to create highly controlled internal environments.

Mixed mode: This approach is characterised by use o both mechanical and passive systemsto achieve a balance between controllability o the internal environment and energy eciency.Buildings and systems are designed in an integrated way to avoid being totally reliant either onmechanical or passive systems. The use o the dierent systems depend on the circumstances, orinstance air conditioning may be used to cool the building during peak summer temperatures,whereas cooling or the rest o the year may be achieved through passive environmental controlstrategies such as night time cooling and cross ventilation.

Passive environmental control: This approach is characterised by maximum use o ambientresources such as sun, daylight, wind and diurnal temperature ranges to create comortable internalenvironments. Buildings are designed to work with these resources and avoid the use o mechanicalsystems. Internal conditions tend to be more variable, refecting changing environmental conditionsbetween day and night and winter and summer.

6.1 Choice o environmental control strategy

The choice o environmental control strategy is dependent on actors such as cost, technical capacity,building unction, client requirements, climate and the local external environment. The maincharacteristics o the active and passive control strategies are outlined below.

Aspects Active environmental controlPassive environmental

control

Control and variabilityo the internalenvironment

Environments can be more highlycontrolled and are generally moreregulated.

Environments are lesscontrolled and more variable

External environment

Mechanical systems can beovercome conditions in harshexternal environments such as thatare very noisy or experience extremetemperatures

This approach is less able toaccommodate harsh externalenvironments such as thosethat are very noisy or polluted.

Links to the externalenvironment

Links and openings to the externalenvironment are generally minimisedto support energy eciency.

Links and openings to theexternal environment are

dependent on conditionsand are controlled tocreate comortable internalenvironments using ambientconditions.

Occupantinvolvement

Occupants are not encouragedto get involved in environmentalcontrol

Occupants are encouragedthrough local controls tomaintain and control theirown comort.

Technical capacitySystems can be complex and requirehigh levels o technical competenceto design and maintain

Systems can be complex todesign, but are generallymechanically simple and easyto maintain


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Reliability o energy

Unreliable energy sources can behighly problematic and powercuts can require the building tobe evacuated. Large standby /

alternative energy sources arerequired to main operations.

Power cuts can beaccommodated and lesspower rom standbygenerators or alternativepower sources is required to

keep the building in operation(i.e. to power emergencysystems and computers).

Maintenance Regular maintenance is crucial.Systems are generally robustand maintenance is simple.

Operational costsOperational costs are generallyhigher than passive systems.

Operational costs are generallylower than active systems.

Capital costsCapital costs o systems are generallyhigher than passive environmentalcontrol.

Capital costs o systems aregenerally less than activesystems (Although buildingabric costs may be higher).

The active environmental control approach relies on achieving the optimum integration betweenbuilding design and ecient mechanical systems to achieve energy eciencies. As technologychanges in this area rapidly and calculations can be complex, suitable expertise should be sought andappropriate modeling should be carried to establish optimum solutions.

In general, this guideline recommends that a passive or mixed mode approach be used in mostbuildings in Johannesburg because this is more energy ecient, simpler to maintain and moreresilient to power outages and shortages. Johannesburgs climate is also relatively mild and constantair conditioning is generally not needed unless specically demanded by the buildings unction andinternal heat loads.

6.2 Active environmental control strategies

Outlined below are strategies that can be used in buildings with active environmental control tosupport energy eciency. Reerence is also made to sections o the guide where urther inormationon the strategy can be ound.

Strategy DescriptionRelevant sections o

the guide

Surace area to volumeratio

The surace area o the building inrelation to the volume is minimised toreduce heat loss or gain through thebuilding envelope.

8.1

Ecient integratedmechanical systems

The building and proposed mechanicalsystems are designed to work togetherin an integrated way to minimise energyconsumption.

10

Zoning and controls

Zoning and controls are developed toadapt mechanical systems to changinginternal requirements and externalconditions.

10.1

Natural or economycycle

During periods o the year when externalair temperatures are comortable,air is circulated through the buildingby the HVAC system without beingconditioned, reducing energy

consumption

10.3


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Sub metering

A system o metering is developed toenable detailed monitoring o energyconsumption in dierent areas o thebuilding.

14.1, 14.2

Building managementsystems

Computers are used to manage dierentbuilding systems in order to ensure thatthese work together in an optimal way.

14.8

Envelope design

Glazing design, insulation and airtightness measures are used to avoiduncontrolled heat losses or gainsthrough the building envelope

8

6.3 Selecting active environmental control strategies

In general, all o the above strategies should be used together to maximize energy eciency inbuildings with active environmental control systems. Particularly important considerations in selecting

HVAC systems include local capacity to design, commission and maintain systems, the adaptabilityand fexibility o the systems, eatures or modes that reduce energy consumption and control andmetering mechanisms that enable close control and monitoring o systems.

6.4 Passive environmental control strategies

Outlined below are strategies that can be used in buildings with passive environmental control tosupport energy eciency. Reerence is also made to sections o the guide where urther inormationon the strategy can be ound.

Strategy DescriptionRelevant sections o

the guide

Solar gainSunlight is used to warm thermal masswithin the building. This releases heatgradually heating the building.

7.6, 7.11, 8.2

Indirect solar gain

Sunlight is used to warm thermal masssuch as a rock bed, which in turn is usedto heat a medium such as air to heat thebuilding.

8.3

Nightime cooling

The building is cooled at night byallowing cool night air to fow to fush thebuilding o hot air and cool the buildingsthermal mass.

8.6

Local controls Occupants are encouraged to adapt theirlocal environment to create comort, orinstance, by opening windows.

4.5

Cross ventilationAir fow through the building is used tocool the building and occupants.

8.4

Stack eect systems

Tall vertical spaces coupled with thephysical tendency or air to rise whenheated are used to ventilate and cool/heat the building.

8.5

Evaporative coolingThe cooling eect resulting romevaporating water is used to cool thebuilding.

7.11

Envelope design

Glazing design, insulation and airtightness measures are used to avoiduncontrolled heat losses or gains throughthe building envelope.

8


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6.5 Selecting passive environmental control strategies

An analysis o Johannesburgs climate indicates that or much o the year conditions in Johannesburgall within a human comort range o between 20-80% relative humidity and 20-26 0 C.

Conditions during winter however can be uncomortably cold and heating is likely to be required. Thiscan be achieved through passive solar heating or most winter months, although there may be daysin May, June, July when temperatures drop below 50 C when conventional heating may be required.These conditions are likely to be experienced at night.

Conditions that may lead to discomort during summer can be addressed through natural ventilation,high mass cooling and shading in buildings. Conventional air conditioning throughout the year is notrequired unless there are stringent temperature and humidity control requirements or high internalheat loads.

Normally a number o passive environmental control strategies will be designed into a building inorder to increase the ability o the building to cope with dierent weather conditions. For instance,both a cross ventilation and a stack eect system may be used to cool the building. During normalconditions when there is a breeze, the cross ventilation system will be eective. However during hot

still conditions when cross ventilation may not be eective, ventilation and cooling can still be achievedthrough the stack eect system.


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Section 7Site


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30

7 Site

The selection o a site is an important component o an energy eciency strategy. Buildings locatednear public transport enable energy expended on transport to be reduced. Similarly, the use o an

existing building will avoid the energy required to construct new buildings. Multi-tenanted buildings(such as fats) are also usually more energy ecient to operate compared to single-occupancy buildings(such as houses) because o the densities achieved. Outlined below are considerations that can be usedin selecting sites and developing site layouts to support energy eciency.

7.1 Location

Sites or new buildings should be chosen where transport energy consumption can be minimised. Thetable below indicates the range in energy consumption or dierent types transport.

Type o transportLitres o uel, or energy equivalent, consumed

per person to travel 100 km

Car (single occupant) 9.00

Car (2 occupants) 4.50

Taxi (12 passengers) 1.00

Bus 0.70

Train 0.50

Walking 1.00

Cycling 0.36

Table 5. Energy consumed per kilometre or dierent types o transportation

From this it is clear that the ideal sites are where occupants can walk or cycle to the building. Othersuitable locations include being near public transport nodes such as bus stops and train stations.Locations where people have to use their cars should be avoided.

7.2 Existing buildings

Where possible, existing buildings should be used and upgraded or improved energy eciency. Thisavoids the substantial amount o energy required to construct new buildings. It also contributes toeciencies within city inrastructure as existing systems are used more intensively and additional newservice inrastructure (water supplies, sewage etc) is avoided.

7.3 Browneld sites

Undeveloped green eld sites should be avoided and already disturbed sites (brown eld sites) shouldbe chosen. This avoids urther reductions in the size, and thereore the capacity, o the naturalenvironment to absorb carbon dioxide resulting rom mans activities. In addition, new developmentsrequire a substantial investment in energy to construct new inrastructure such as roads, power andcommunication networks and water, sewerage and storm water systems.

7.4 Building orientation

Buildings should be orientated to avoid unwanted heat losses or gains. In general, the long section obuildings should be orientated to +/- 15 degrees North. In addition, the extent o the aade acingnorth should be maximized and the length o aade acing east and west minimised. This enablesgood access to sunlight or the north aade, good access to daylight through the north and south

aades and reduces unwanted heat gain rom early morning and late aternoon sunshine on the eastand west aades.


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7.5 Access to light

Buildings should be arranged on site to ensure that they have good access to daylight and do notshade close neighbours. Obstructions in ront o windows can severely reduce the quality o daylightin spaces. The quality o daylight in a space relates to the visible sky angle measured rom the centre

o a window on an external wall. The larger this angle the better the daylight quality will be in thespace. The no skyline position is the location on the working plan (0.85m above foor in residential and0.7m above foor level in oces) where the sky can no longer be seen. Space to the interior o this willusually requires supplementary electrical lighting.

No-sky lineposition

Figure 5. Diagram indicating no-sky position in a building

7.6 Access to sunlight

Buildings should be arranged on site to ensure that spaces and equipment that require high qualitysunshine are provided with good access to this. This includes external and internal spaces designed tobe heated by the sun and areas with solar water heaters or photovoltaic panels.

7.7 Access to ventilation

The layout o buildings on site and the landscaping strategy should ensure that buildings have goodaccess to breezes where this is required to cool and ventilate buildings. Landscaping can also be usedto provide windbreaks to create comortable protected external spaces and reduce heat losses rombuildings in winter.

7.8 Noise

I the site is adjacent to noisy areas such as highways, the site layout should be developed to maximisethe distance o buildings to this. In addition, earth berms or non-occupied buildings such as parkinggarages and electrical substations can be used as a sound buer. This helps reduce the requirement orhigh perormance glazing and may allow more windows in the building to be openable.

7.9 External hard surace and car parking

Large areas o hard suraces such as paving and parking can contribute signicantly to increasedtemperatures around building. This is reerred to as the urban heat island eect and the retainedheat and resultant higher air temperature make it more dicult to keep buildings cool. This can beaddressed in the ollowing ways:

Avoiding large areas o external hard suraces near buildings Shading parking and hard suraces, ideally using vegetation such as large shade treesUsing lighter coloured materials or paving and external suraces to reduce the extent to which

these suraces absorb heat


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7.10 Cycling and walking

Cycling can be 30 times more energy ecient (see table 5 on page 30) than using a car. Cycling andwalking are also the only readily available orms o transport that use renewable energy and supporthealth and productivity. Cycling and walking can be supported in the ollowing ways:

Providing dedicated cycle and pedestrian paths around your siteDeveloping a driver education campaign and signage to ensure that vehicle drivers are mindul and

courteous o cyclist Providing secure cycle parking in appropriate locations Providing showering and changing acilities in buildings

7.11 Comortable outside spaces

Comortable external spaces can be used to create stimulating and contrasting environments or workbreaks. Comortable outside spaces can contribute to energy eciency by helping condition (cool orwarm) air beore this is drawn into buildings. They also provide useul additional working, meeting oreating spaces that require very little energy to maintain. Key considerations in developing these spaces

are listed below:

The spaces should be close to buildings. Spaces should be sunlit and protected rom cold winds in winter to ensure that these are

comortable. Spaces should be shaded in summer and away rom heat or noise generating areas such as large

cars, plant and roads with ast-moving trac.Additional cooling in summer can be provided rom evaporative cooling rom ountains and water

suraces.

7.12 Access to acilities

Locating acilities such as caes, restaurants, post boxes, telephones, schools, gyms, banking and retailoutlets within or near residential areas or places o work support energy eciency by enabling peopleto walk to these acilities rather than use their cars.

7.13 Neighbouring sites

Site layouts should be developed to avoid negatively aecting a neighbouring buildings access tosunlight, daylight and ventilation. Ideally, site plans they should be developed in conjunction withneighbouring sites in order to create an integrated master plan that supported energy eciency.Examples o areas that could be collaboratively explored include:

Shared car parking space and transportation systems (such as company buses) Linked pedestrian and cycle routes Integrated building layout and landscaping that developed benecial microclimates Integrated storm and waste water management that enabled moisture to be retained on site and

contributed to evaporative cooling


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Section 8Building orm and envelope


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8 Building orm and envelope

8.1 Surace area to volume ratio

In buildings which have active environmentally control it is important to minimise heat gains and lossesthrough the building envelope. One way o reducing this is to minimise the surace area o the buildingrelative to its volume. The surace area to volume ratio is calculated by divided the volume o thebuilding (in m3) by the surace area o the building (in m2). Simple compact buildings achieve the bestratio, as illustrated below.

Volume 27 27

Surace area 54 78

Volume to surace area ratio 0.5 0.34

Figure 6. Diagram showing surace area to volume ratio or dierent building shapes

8.2 Direct solar gain

Sunlight is a ree heat source that can be used to reduce the requirement or heating in buildings oncold days. The simplest way o harnessing this resource is to allow sunlight to enter buildings whenheating and warm high thermal mass areas, such as exposed masonry walls or tiled foors. The thermalmass stores this heat and releases it gradually, keeping the building warm. In general, direct solar gainsystems should not be used to heat spaces where people where working on computers and whereglare may be a problem. In these areas direct solar gain can be used to warm non-working spaces suchas circulation and pause areas near working spaces. The ollowing actors should be considered inharnessing solar gain:

Location and orientation: Location and orientation o the building to ensure good solar access atthe right times o the year.

Building envelope: Openings, glazing (and possible blinds and curtains) in the building should bedesigned to direct solar access to the right area and retain heat gathered.

Material and nishes: The location, colour and type o nishes should be selected to providegood thermal storage.

8.3 Indirect solar gain

More complex, but more controllable passive solar heating systems are indirect solar gain systems.These use the sun to warm high thermal mass materials such as rock or water. This heat is then storedand circulated to the building using air or water as a medium. These systems can be complex to designand key considerations include:

Location: Location o the indirect system to ensure that is near the building and has good solaraccess.

Sizing: The collection area, thermal storage capacity and heat circulating system needs to be sizedcorrectly.


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8.4 Cross ventilation

Cross ventilation is an energy ecient way o cooling buildings in areas where there are moderatebreezes. Airfow through the building is used to remove heat and bring in resh air. The ollowingactors should be considered developing buildings with cross ventilation:

Landscaping and building layout: Care should be taken to expose aades with openingwindows to breezes and to avoid these being in the wind shadow o other buildings andobstructions.

Depth o the buildings: The depth o the building should not be more than 12-15m. Internal spatial layout: Air movement should be directed around people and the breeze path

between windows on opposite walls be made a direct as possible to ensure that air movement iseective.

Figure 7. Diagram showing cross ventilation in a building

8.5 Stack eect systems

A stack eect system uses tall vertical spaces and the physical tendency o warm air to rise to ventilateand warm or cool buildings. Rising air within a vertical space, which could be an atrium or solarchimney, is used to draw air into buildings, ventilating it. This air can be drawn rom a cool source,cooling the building, or rom a warm source, warming the building. The ollowing actors should beconsidered in developing stack eect systems:

The stack eect chimney: The taller this space is the more powerul the system will be. Aminimum o 9m is usually required or eective systems.

Location: The vertical space should be located adjacent to spaces to be cooled or heated.

Heat sources: Stack eect systems can be assisted rom heat sources such as the sun, people andequipment. The design and location o the stack eect system should harness these heat sources.Controls: To control air movement and the extent o heating and cooling.

8.6 Nighttime cooling

Nighttime cooling uses the diurnal range to cool buildings. During the night cooler air is used to fushwarm air out and cool the thermal mass o a building. The ollowing actors should be considered indesigning or nighttime cooling:

Openings: The design and location o openings should enable good airfow at night through thebuilding. Airfow should be directed around thermal mass in order to remove heat at night.

Security: Care should be taken to avoid compromising security.Thermal mass: The location o thermal mass within the building where it can act as heat sink

during the day and be cooled by night-time ventilation.


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8.7 Day lighting

Good day lighting reduces energy consumption by minimising the requirement or articial lighting.Daylight strategies should consider the ollowing actors:

Access to day lighting: Landscaping and building location to ensure good access to daylight.Depth o the buildings: The depth o the building should be limited to ensure that internal spaces

that cannot be day lit are limited in area. A general rule o thumb is that daylight quality will bereasonable within the space 2h rom a window, where h is the height o the head o the windowrom foor level (see gure 8below).

Type o glazing: Selection o glazing to allow good daylight penetration. Light shelves: The use o daylight shelves to enable daylight penetration deeper into the building. Internal colour: The choice o colour and nishes to improve internal refectance o spaces.

2H

H

Figure 8. Diagram showing area o high quality daylight

8.8 Shading devices

Shading devices should be used to avoid unwanted heat gains. The design o shading devices arenormally based on calculations and modelled to ensure that windows or glazing is shaded rom directsunlight at specic times. In general, horizontal shading elements are appropriate on northern aadesand vertical moveable louvers are suitable on east and west aades. On the northern aade shadingdevices can be designed in accordance with the diagram below.

50

26

Figure 9. Diagram showing sizing o horizontal shading device on south aade (SANS 204)


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37

A

A

Figure 10. Diagram showing extent to which horizontal shading device should extend beyond the edgeo windows (SANS 204)

The section shows the angle o the sun at the equinox (around March 20and September 23 each year)when the sun is directly over the equator. This angle (26 0) can be used to set out the sill o windows.The angle o the sun at the winter solstice (around June 20) can be used set the head o the window(500). The depth o the shading device (A) should be where these angles meet. The shading deviceshould extend beyond the window below by at least length (A) to be eective.

While the above illustrates an approach to designing solar shading on a north aade, it is importantor designers to calculate and model solar shading to suit their particular site and building type. Forinstance, an spaces with computer screens may require solar access to be avoided altogether becauseo visual and glare problems, whereas a passive solar house may require good solar access during thewinter months to heat the house.

8.9 Colour

The colour o building aects the extent to which it absorbs heat rom sunlight with darker coloursabsorbing more heat than lighter colours. Thereore, in general, building envelopes should be lightcoloured, particularly roos and east and west aades.

Colour Value

Slate (dark grey) 0.9

Red, green 0.75

Yellow, bu 0.6

Zinc aluminiumdull 0.55

Galvanised steeldull 0.55

Light grey 0.45

O white 0.35

Light cream 0.3

Table 6. Absorbencies o dierent colours (SANS 204)


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8.10 Insulation

Insulation can be used to reduce the heat fow through the building envelope. Detailed guidance onthis can be ound in SANS 204. In addition, many insulation manuacturers will undertake calculationsto assist in determining appropriate envelope build construction, including the type, thickness and

location o insulation. There are however some general guidelines:

Most heat losses and gains are through the roo o buildings; this is thereore the place whereinsulation will have the most eect.

In order to maximise the thermal fywheel eect in buildings, insulation should be located on theoutside o high thermal mass envelopes and building structures.

The thermal resistance o building envelopes can be increased easily and at low cost throughdesign. For instance, the incorporation o an air gap within a wall build-up or planting creepers onan external aade use the insulative properties o air to increase thermal resistance o the buildingenvelope.

Care should be taken to ensure that insulation is as continuous as possible within a buildingenvelope and gaps and thermal bridges should be avoided.

Minimum insulation levels or dierent areas o the building envelope are provided.in SANS 204.These should be complied with and exceeded, where appropriate.

8.11 Glazing in aades

The amount, type and location o glazing can have a signicant eect on energy consumption usedin building or lighting, heating and cooling. The ollowing guidelines can be used to support energyeciency:

The area o glazing on a aade should be an optimal balance between daylight quality and heatgains and losses. Glass generally has a much lower R-value than solid walls. Thereore in highlyglazed areas it may be dicult and expensive to control heat gains and losses. I areas are goingto be highly glazed, high perormance glazing should be investigated in order minimise discomortand energy consumption (see below).

Where possible, glazing should be avoided on east and west aades to avoid unwanted heat gains.

Glazing should also be placed where it provides views and higher up in walls to support good daylighting.

8.12 Windows

Well-designed windows can improve the energy eciency through enabling good daylight and naturalventilation. Characteristics o windows that can be used to support energy eciency are outlinedbelow:

Where windows are being used as part o a cross ventilation strategy, the size and location oopening sections should be designed to ensure that breeze paths through the building are directand are guided through areas, equipment and people that need ventilation and cooling.

Naturally ventilated buildings should have an equivalent opening area (o windows or doors) o atleast 5% o the foor area.

Light coloured chamered reveals help reduce contrast between windows and surrounding wallsreducing glare and improving day lighting.

Windows with opening sections at both high and low level benet rom being able to use the stackeect to create air movement and can be used to vent hot air out o the top o rooms and draw incooler air in at low levels.

Window opening controls should be designed to give occupants control over their localenvironment. This can be done by having regularly spaced windows and providing at least oneopening section per 5 m o aade. Window controls should also cater or people with disabilities


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Section 9Internal space


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9 Internal space

9.1 Functions

Locating unctions in a building careully can enhance energy eciency by working with environmentalconditions within and around the building, rather than against these. An outline o the environmentalconditions experienced in dierent areas o a building, with suggested unctions, is given below.

Area o the

building

Environmental

conditions

Appropriate

unctions: oce

Appropriate

unctions:

residential

East acingWill receive low anglesunlight and heat gainin the morning

Canteens, kitchensKitchens, diningareas, bedrooms

North acing

Will receive varyinglight throughout andsunshine throughoutthe day

Work areas, (highthermal mass elementssuch as stair cases ipassive solar strategyused)

Living, working

areas (high thermalmass elementssuch as stair cases passive solarstrategy used)

West acingWill receive low anglesunshine and heatgain in the aternoon

WCs, storage, serviceareas, lit shats,staircases

Bathrooms, WCsstorage areas

South acing

Daylight conditionswill be even acrossthe day and relativelylittle sunshine will be

received.

Working areas,circulation, services,meeting areas

Bedrooms,circulation, services

Core o the building

Daylight and naturalventilation are likelyto be relativelypoor (withoutroo openings).Temperatures remainairly steady

Lit shats, stair cases,circulation, storage

Storage, circulation

9.2 Ventilation

Areas such as WCs and bathrooms that require good ventilation should be located on external walls

to maximise the use o natural ventilation. Similarly, spaces with high internal heat gains rom peopleor equipment should be located on or near an external wall in order to enable this heat to extracted tothe outside in an energy ecient way, or instance through high level windows or vents.

Where possible, parking should be designed to rely on natural ventilation. In large undergroundparking areas where natural ventilation cannot be achieved, carbon dioxide detectors can be used tocontrol mechanical ventilation systems to avoid over ventilating space when this is not required.

9.3 Thermal mass

Thermal mass can provide a useul fywheel eect in buildings by storing warmth rom the solar gain,people and activities. This warmth is released gradually, increasing temperatures in the late aternoonand evening.


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Thermal mass can also be used to store coolth rom cool nights to reduce temperature increasesduring the day rom solar gain, people and activities by acting as a heat sink and absorbing heat. Thereare number o actors that should be considered in design systems that include thermal mass. Theseare outlined below:

The easiest way to achieve thermal mass is through inclusion o high thermal mass materials suchas concrete, stone, ceramic tiles and brick in the construction o the building. Thermal mass is most eective i its surace area has maximum exposure to the internal

environment and it is located within an insulated building envelope.Using ceramic tile or screed foor nish and exposing masonry walls and concrete roo structure is

an ideal way to increase the eectiveness o thermal mass in a building. Covering-up thermal massin buildings through the use o carpets and ceilings should be avoided.

For good winter perormance, thermal mass should be exposed to direct sunlight and is bestlocated behind with unobstructed north-acing glazing.

Nighttime cooling is most eective when cool night air is directed against thermal mass to absorbheat gained during the day. Design or nighttime cooling should thereore ensure that openingsand air movement is directed over thermal mass to ensure that heat gains are eective removed.

9.4 Internal walls

The location and design o internal wall should be considered careully in buildings with passiveenvironmental control. In particular the ollowing actors should be considered:

In buildings where cross ventilation is used, internal walls should not to impede airfow. This can beachieved by designing walls to run parallel to airfows, creating a space above or below walls orair movement and including openings within walls, such as doors with openable lights. In buildingswhere privacy requirements make normal cross-ventilation strategies dicult, ceiling voids can beused to enable cross ventilation while still ensuring privacy.

High thermal mass walls, such as concrete and brick walls located around stairs, lits and bathroomscan contribute to improving the thermal mass o the buildings and can be located and designed tocontribute to passive environment control strategies.

9.5 Finishes

Light coloured high thermal mass nishes can help reduce energy consumption by supporting gooddaylight quality and passive environmental control strategies. Darker coloured foors in areas with directsolar gain are suitable in order to maximise heat absorption.


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Section 10Mechanical systems


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10 Mechanical systems

Energy costs in a typical air-conditioned building are usually at least double the energy costs andassociated CO2 emissions o a building with passive environmental control (Carbon Trust 2006).

Increased capital and maintenance costs are also likely (Carbon Trust 2006). Thereore mechanicalheating and cooling systems should be avoided, where possible. The chart below can be used ascertainwhether a mechanical system is required.

Figure 11. Factors infuencing type o environmental control system (Adapted rom Carbon Trust)

10.1 Zoning

Zoning a building into dierent areas depending on ventilation and heating and cooling requirementscan enable mechanical systems to be used more eciently. Thus an area with high ventilationrequirements and heat gains such as a kitchen could be zoned and dealt with separately to other areas

such as passageways, or storage where ventilation requirements are lower. Zoning also allows heating,cooling and ventilation to dierent areas o the building to be reduced to match requirements moreclosely.

Design teams should work closely with building developers and occupants and in order understandhow the building will unction and relate to the external environment in order to develop zoning andcontrol systems that support energy eciency.

10.2 Pre-heating and pre-cooling

Heating and cooling systems can be made more ecient by linking these to systems which pre-cool orpre heat air. For example, a heat exchanger can be used to extract heat rom exhaust air rom a kitchenor gym and use this to warm incoming resh air.


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10.3 Natural or economy cycle

External air temperatures in Johannesburg are comortable or a large part o the year. Energyeciencies can be achieved by using this air directly to ventilate buildings without conditioning it. Thisis sometimes reerred to a natural or economy cycle and can be used to achieve substantial energy

savings.

10.4 Mechanical ventilation

Mechanical ventilation should be avoided where possible through the use o passive ventilationstrategies. There are however situations where mechanical ventilation cannot be avoided. This includesspaces such as internal kitchens, underground parking, toilets and server and print rooms. In order tomaximise the energy eciency o mechanical ventilation in these areas the ollowing actors should beconsidered:

Spaces should be located as near as possible to an external wall in order to minimise the distanceair has to be extracted.

Ducting design and an specication should be carried out to minimise energy consumption.Controls such as movement sensors, CO2 monitors and timers should be used to ensure that

spaces are not over-ventilated when not in use.

10.5 Exhaust ans

Exhaust ans can result in uncontrolled air movement in and out o the building when not in use. SANS204 thereore requires exhaust ans in conditioned spaces to be tted with a sealing device such as asel-closing damper to prevent this.

10.6 Vertical transportation

In large buildings the use o lits and escalators may be unavoidable, however in smaller buildingspeople should be encouraged to use stairs or ramps to move between dierent levels. This reducesenergy consumption in buildings and has the added advantage o providing exercise. The easiest wayo encouraging people to use stairs is to locate them and design them so that they are easier to usethen lits or escalators.


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Section 11Electrical lighting


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11 Electrical lighting

Electrical lighting systems vary widely and it is important to select the most appropriate system or yourapplication. In particular the ollowing issues should be considered:

Light level requirements: Required light levels or dierent areas are outlined in SANS 10400 andshould be ollowed.

Saety: Requirements or emergency egress and compliance with the Occupation Health andSaety Act should be ensured.

Energy eciency: Energy ecient lighting systems should be selected. Good indicators o energyeciency are luminous ecacy and energy requirements per m2 (see below).

Colour rendering: The extent to which colours are rendered eectively can be important,particularly in museum, art gallery and retail environments.

Maintenance: The cost o replacing lamps can be considerable, particularly in dicult-to-accesslocations such as atria or auditorium roos. The liespan o lamps may thereore is an importantactor.

11.1 Lamp selection

The selection o lamp has a major infuence on energy eciency. A good indicator o energy eciencyin lamp selection is the luminous ecacy in lumens per Watt. This inormation or dierent lamp typesare provided below. The use o tungsten and halogen lamps, the least energy ecient lamps, shouldbe minimised.

Type Overall luminous

Ecacy (lm/w)

Lie span

(Hours)Applications Notes

Tungsten 7 - 24 700-1000 General lightingLeast ecientlamp

Halogen 12 - 36 2,000 - 4,000 Generallighting, accentlighting

Bulb burns very

hot, care shouldbe taken aboutlocations

CompactFluorescent

45 - 90 Up to 10,000 General lightingVery ecient,readily available

Fluorescent(tubular)

50 - 10010,000 -20,000

General lightingVery ecient,readily available

WhiteLED

30 - 60(200)

30,000 -80,000(100,000)

Generallighting, Accentlighting

Rapidly changingtechnology(gures inbrackets arepredicted

perormance innext ew years)

Metalhalide

60 - 125 6,000 - 10,000Retail, sportsacilities, arenas,convention halls

Good colourrendering

MercuryVapor

20 - 63 1600 - 6000Outdoorlighting

Produces bluegreen light, poorcolour rendering

HighPressureSodium

60 - 14018,000 -24,000

Outdoor,industriallighting

Produces yellowlight, poor colourrendering

Low

PressureSodium 90 - 180

Approximately

16,000 Security lighting

Very poor colour

rendering

Table 7. Lamp eciencies


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11.2 Zoning and circuits

The design lighting systems should ensure that lighting is only used on when required. It should alsoensure that only the specic area where lighting is needed is lit. The situation thereore o having awhole foor lit to accommodate one person working late should be avoided.

11.3 Lighting maintenance

The accumulation o dust and dirt on light ttings and lamps can reduce their eectiveness by up to40%. The design o lighting should thereore ensure that light ttings and lamps can be easily accessedand cleaned.

11.4 Lighting controls

Lighting should be switched o when not needed. This can be done manually or automatically. Theollowing actors should be considered when designing lighting controls:

Location: Light switches should be located in prominent positions on routes out o rooms and

passageways, and as you exit the building, as a whole.Zoning: Lighting should be zoned into logical areas that can be switched on and o individually.

Generally lighting zones should not be restricted to the size o the room in closed planenvironments and to less than 100m2 in open plan environments.

Daylight sensors: daylight sensors can be used to dim or turn-o lighting when there is adequatedaylight.

Nighttime switching: External lighting should be linked to daylight sensors or timers to ensurethat this is on only when needed.

Movement sensors: Movement sensors can be used to automatically switch o lighting in spacesthat are not being used.

Timers: Timers can be used to ensure lighting is on or specied time only. For instance, externallights can be designed to switch on between 6.00 and 10.00 PM when external spaces are usedand then switched o or the rest o the night.

11.5 Energy consumption

Energy consumption in lighting should be evaluated against best practice benchmarks. A benchmarkthat can be used are the power density and maximum average annual energy consumption guresoutlined below rom SANS 204.

Class o

occupancy

or

building

Occupancy Population

Recommended good practice

maximum values

Power

watts per

m

Energy

kilowatts-

hours per

annum per m

A1Entertainment &Public assembly

Number seats or1 person/m

10 25

A2Theatrical &indoor sport

Number seats or1 person/m

10 25

A3Places oinstruction

1 person / 5 m 10 25

A4 WorshipNumber seats or1 person/m

10 10

A5Outdoor sport is

viewed

Number seats or

1 person/m10 15


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B1High riskcommercial

1 person / 15 m 24 60

B2Moderate riskcommercial

1 person / 15 m 20 50

B3Low riskcommercial

1 person / 15 m 15 37.5

C1 Exhibition Halls 1 person / 10 m 15 22.5

C2 Museums 1 person / 20 m 5 12.5

D1High riskindustrial

1 person / 15 m 20 50

D2Moderate riskindustrial

1 person / 15 m 20 50

D3Low riskindustrial

1 person / 15 m 15 37.5

D4 Plant rooms 5 5

E1Places odetention

2 person /bedroom

15 37.5

E2 Hospitals 1 person / 10 m 10 87.6

E3Otherinstitutionalresidences

1 person / 10 m 10 25

F1 Large shops 1 person / 10 m 24 105.12

F2 Small shops 1 person / 10 m 20 87.6

F3Wholesalersstore

1 person / 20 m 15 65.7

G1 Oces 1 person / 15 m 17 42.5

H1 Hotels2 person /bedroom

10 43.8

H2 Dormitories 1 person / 5 m 5 12.5

H3Domesticresidences

2 person /bedroom

5 5

H4 Dwelling houses 4 person / house 5 5

J1 High risk storage 1 person / 50 m 17 42.5

J2Moderate riskstorage

1 person / 50 m 15 37.5

J3 Low risk storage 1 person / 50 m 7 17.5

J4Parking areascovered

1 person / 50 m 5 21.9

Table 8. Recommended light levels, power and energy or the classes o buildings


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Section 12Water heating


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12 Water heating

Electrical geysers use up to 40% o a homes energy consumption (Eskom 2006). Thereore reducingthe consumption o hot water and using solar energy to heat water and can be make a signicantcontribution to energy eciency.

12.1 Solar water heating

A highly energy ecient way o heating water is through solar water heaters. A 150L solar waterheater will replace about 4.5kWh/day o electricity, which saves 2 tonnes o carbon emissions per year(Eskom 2006)

Solar water heaters should comply with the requirements o SANS 1307 and be installed in accordancewith SANS 10106. Solar water heaters can be used in all areas o South Arica to provide hot waterthroughout the year. The design and sizing o the system should be carried out in conjunction with asolar water heater supplier, however the ollowing issues are common to most solar water heaters:

Solar collectors should ace true north, i possible. Deviations o 45o East and West can usually can

be accommodated. The pitch (angle rom horizontal) o the solar collector should normally be latitude o the location

plus 10 o , so collectors in Johannesburg would be angled at 36 o .

Solar collectors should be positioned where surrounding buildings or trees will not shade them.Small obstacles such as TV aerials do not have much eect.

Solar collectors are most eective when they are clean. As these tend to get dusty ensure that theyare located where they can be cleaned regularly.

When ull o water, solar heating systems will have a considerable weight and sucient structureshould be provided to take this.

12.2 Pipe runs

The distance between hot water storage or generation and use should be as short as possible in order

to minimise heat losses rom hot water pipes. This also helps reduce water consumption, as largeamounts o cold water are not drawn o beore hot water reaches taps.

12.3 Insulation

Hot water pipes and storage units should be insulated to minimise heat losses. Levels o insulationshould be provided in line with SANS 204 and are outlined below.

Internal diameter o pipe Minimum R-value

Internal piper diameter 40mm and lessInternal piper diameter exceeding 40mm, but not exceeding80mm

Internal piper diameter exceeding 80mmHot water cylinder or storage

0.6251.001.50

2.00

Table 9. Minimum R-values or pipe insulation

12.4 Hot water temperatures

The temperature o hot water should be suitable or its use. Normal washing can be done withwater at 550C. Setting the thermostat at the right temperature can improve energy eciency. Forinstance, lowering the temperature o an electrical geyser rom 700C to 600C can reduce the energyconsumption by about 5% (Eskom 2006).


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12.5 Hot water consumption

Hot water consumption should be minimised by speciying water ecient delivery devices. Forinstance, showers should be specied in preerence to baths. Guidelines targets or hot waterconsumption in dierent water delivery devices are provided below.

Water delivery device Maximum fow/water consumption

Showers 6-7 litres/min

Clothes washing machines 50 litres per wash o 5 kg cottons.

Dishwashing 18 litres per load

Hand basins taps 2 litres/min

Table 10. Maximum fow and water consumption in water delivery devices

12.6 Hot water energy targets

The design o hot water systems should be checked against benchmarks to ensure that they are energyecient. Annual domestic hot water heating power densities required by SANS 204 are providedbelow.

Occupancy Heating power density (W/m2)

Residential 9.61

Hotels & guest houses 4.65

Hospital 20.00

Oce 0.23

Retail 0.14

Table 11. Annual domestic hot water heating power density


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Section 13Appliances and equipment


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13 Appliances and equipment

Appliances and equipment used in buildings should be as energy ecient as possible. As technologyin this area changes rapidly it is worth investigating the latest energy consumption eatures and

comparing dierent models in order to identiy the most ecient.

13.1 Ratings and controls

There are rating systems or energy eciency in appliances and equipment such as energy star. Theseratings and eatures such as standby modes can be used to help identiy the most energy ecientequipment.

13.2 Domestic appliances and equipment

An indication o the average energy consumption or domestic appliances is provided below. The highlevels o energy consumption or swimming pool pumps and air conditioners should be noted in orderto avoid these i possible.

ApplianceAverage

kWh p/a

Swimming pool pump 2020

Air conditioner (room) 1070

Colour television (on) 197

Computer 130

Coee maker 100

Stereo/radio 75

Hair dryer 50

Ceiling an 50

Iron 50

Video machine 40

Telephone 36

Answer machine 36

Colour television (o) 33

Vacuum cleaner 25

Table 12. Energy consumption in domestic appliances

13.3 Oce equipment

Increasingly oce equipment has energy ratings and includes energy saving eatures. The ollowingissues should also be considered in selecting equipment.

Monitors: Consider using fat screen monitors that emit less heat, use less energy and space thanconventional monitors.

Computers: Consider using laptops instead o conventional desktops. These use about 10% othe energy o desk tops and can also promote energy eciency through reduced travel by enabling

remote or home working.Photocopiers and printers: Seven day timers can be used to ensure that these are switched o at

night or on weekends when they are not being used. They should also be positioned in areas withgood natural ventilation and airfow to avoid air conditioning costs and the build up o umes.


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Section 14Integrated control systems and monitoring


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14 Integrated control systems and monitoring

In order to maximize energy eciency in buildings adequate controls and monitoring and meteringsystems need to be in place. These enable users o buildings to only use electrical systems or parts

o electrical systems when they are needed. It also enables users to track energy consumption anddevelop targets and strategies to reduce this over time.

14.1 Meters

Electricity meters should be located where they can be easily read. Energy consumption inormationshould be shared with building users through notice boards and intranet sites in order to ensure thatthey are aware o levels o consumption and are able to take responsibility or reducing this.

14.2 Sub-metering

Where systems, such as mechanical heating and cooling, consume over a third o the buildingsenergy consumption it can be benecial to sub-meter and monitor these systems. Sub metering and

monitoring have been ound to save at least 5% o yearly energy costs (Carbon Trust 2006).

14.3 Switching and controls

The switches and controls or electrical equipment and lighting should be made easy to use andlocated in areas that are easily accessible to the person responsible or using these. A simple instructionmanual and training should be provided in order to ensure that people who manage buildingunderstand how and where energy consumption is consumed and how this can be minimised throughmanagement.

14.4 Thermostats

Most air-conditioned areas do not need to be cooler than 24oC and a temperature o 19 oC set

or heating to be initiated. This can be used to develop dead band setting o 19-24 oC where nomechanical heating and cooling takes place (Carbon Trust 2006). This type o setting can help increaseenergy eciency without signicant impacts on comort. Thermostats on electrical geysers used orproducing water or washing should normally be set at 55oC.

14.5 Daylight sensors

Daylight sensors can be used to reduce energy consumption by electrical lighting. This requires thatelectrical lighting within areas that normally receives good daylight are zoned so that lighting caneasily be switched o or dimmed when there is adequate daylight. This can be done manually throughwell-located switches and building user awareness training or automatically through daylight sensors.All external lighting should be linked to daylight sensors to ensure that this is switched o during thedaytime.

14.6 Movement sensors

Movement sensors can be used to ensure lighting is switched o when spaces are not being used andcan be used in a wide range o applications including oce areas, meeting rooms, toilets, car parking,storage areas and external routes around a building. Movement sensors can also be used to switch onmechanical extract ans in spaces such as bathrooms while they are occupied only.


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14.7 Timers

Timers can be used to switch o electrical equipment when it is not used and can be applied to manydierent situations to reduce energy consumption. Some examples are provided below:

Oce equipment such as photocopiers and printers can be put on a seven-day timer, whichswitches o equipment at night and on weekends when not in use. Electrical geysers can be linked to timers, which switch geysers o and on when hot water is

required. Feature and architectural lighting: Timers can be used to switch lighting on when necessary, or

instance in the early evening, and then o or the rest o the night. Timers can be used to use electricity only at o-peak times (such as at night). Dishwashers, washing

machines and pool pumps could be switched on and o in this way.

14.8 Building management systems

In complex buildings that consume large amounts o energy it is worth having a building managementsystems that enable electrical systems to be closely controlled and monitored.


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Section 15Useul checklists and inormation


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15.1 Oce design checklist

Aspect Design process and eaturesSel

assessment

1 Targets Does the brie require that challengingand specic energy targets are set andachieved? Is there a monitoring andevaluation process in place or this?

2 Occupants Is energy ecient occupant behaviorbeing encouraged? Is a building usermanual and an appropriate d

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