Sustainability Program for Community Housing Organisations Compass Housing Services This project has been assisted by the New South Wales Government through.
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Sustainability Program for Community Housing Organisations
Compass Housing Services
This project has been assisted by the New South Wales Government through its Energy Efficiency Training Program
Copyright and disclaimer The Office of Environment and Heritage and the State of NSW are pleased to allow this material to be used, reproduced and adapted, provided the meaning is unchanged and its source, publisher and authorship are acknowledged. The Office of Environment and Heritage has made all reasonable effort to ensure that the contents of this
document are factual and free of error. However, the State of NSW and the Office of Environment and Heritage shall not be liable for any damage which may occur in relation to any person taking action or not on the basis of this document. Office of Environment and Heritage, Department of Premier and CabinetPhone: (02) 9995 5000 (switchboard)Email: info@environment.nsw.gov.auWebsite: www.environment.nsw.gov.au
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Thermal performance
• How energy comes into, around and out of our homes
• Maintaining interior comfort levels
• How behaviour can heavily influence energy and cost
• Largely determined by building design
• 78 images
Achieving thermal comfort
Thermal comfort is achieved by having your body in equilibrium- the heat coming onto the body matches the heat leaving the body.
Thermal comfort is subjectivePeople feel heat differentlyGenerally, People from the UK find the climate here very warm – hotPeople from the equatorial countries- i.e. Singapore generally find climate here cool.
How we are conditioned can have a big effect on heating or cooling costs.
Heating and cooling expectations are now much greater then they used to be.
Heat Movement
It is important to understand the 4 methods of heat transfer.•Radiation. Heat transfer through space, and heating only the object that catches the radiation •Convection. The movement of air due to the fact that warm air is lighter than cool air. •Conduction. Heat transfer through direct contact between warm and cool objects.
Evaporation
The other major method of heat exchange,•It is extremely effective at cooling•Water absorbs a very large amount of heat (2.3MJ/litre)or .6KWh/l
That is why•Sweating is so effective, •Breezes are so refreshing in summer.
Evaporation depends on lower levels of humidity.•That is why evaporative air conditioners are common inland•But not along the relatively humid coastal strip.
Passive solar design-What is it???
A method of controlling the internal temperature of a building by using appropriate design principles.
Features of passive design?•Creates comfortable living conditions while avoiding the use of expensive appliances for heating and cooling•Free heating from the sun during winter•Shielding house from sun in summer keeping it cool•Makes use of the cooling breezes in summer •Passive because the house design self regulates temperature
•The best results are gained by active occupants
Seasonal variation of the Suns path
Ideally a long face of the building faces north for maximum solar control•Note shadow length and angle of sun. •Many streets-full of existing houses are already orientated the right way, and are relatively easily adapted.
Thermal mass- examples
MATERIAL THERMAL MASS(volumetric heat capacity, KJ/m³.k)
Water 4186
Concrete 2060
Sandstone 1800
Compressed earth blocks 1740
Rammed earth 1673
FC sheet (compressed) 1530
Brick 1360
Earth wall (adobe) 1300
AAC 550
Source: EDG
Eaves and solar control
http://www.yourhome.gov.au/technical/fs45.html
Essential features for passive solar function
• Correct orientation of windows -for allowing or rejecting solar heat. (Mostly on north side)
• Ventilation for summer cooling• Thermal Mass for storing heat or cool• Insulation to resist heat flow- in , or out• Shading by eaves and vegetation -sun control
Reverse Brick VeneerReverse brick- veneer is a perfect building system to use in mixed climate zones.A mixed climate zone is where it is often too hot in the summer, and too cold in the winter i.e. most of southern Australia.
General Layout priorities
• East– west orientation, with long face either front or back• Living rooms toward the north side• Lesser used rooms to the south- • More windows to the north, easy solar control• Less windows to the W, E, and least to the south.
Credit: yourhome
Design example- Every room has solar access
North
• Large windows along north face• Thermal mass along front for heat control• Windows allow breezes• With good insulation, energy bills close to ZERO for heating and cooling
Credit: Ian Garradd, Madhan Sekar
Site analysis and solar potential zero energy home. -A feasibility study, Tasmania.
• All energy and water could come from the building
Images: Ian Garradd
Eventually all buildings are likely to be carbon neutral in their operation
Images: Henley Homes, Delfin, Lend -Lease
This is one recently built in Melbourne by some progressive developers. …It looks just the same as any other well- designed home.
Compass north is not true north
The best orientation for passive solar design is TRUE north, or GRID north, often referred to as SOLAR north
Credit: Google earthCredit: yourhome
Does it apply to existing buildings?
While in practice, we will be mostly dealing with existing housing, it is essential to be familiar with the major elements of natural heating and cooling….
•as it is possible to adapt most buildings to harness at least some of the free heating and cooling potential.
•It is important to consider passive solar energy potential when either buying , or renting a house, as it will have a large impact on the cost of living of the occupant$.
Building energy ratings to come
• Indications of energy required to keep house interiors comfortable• The A.C.T. has been using mandatory energy ratings since 1999
(in the ACT)
National home energy ratings
What the stars mean
•Zero stars means the building shell does practically nothing to reduce the discomfort of hot or cold weather.
•A 5 star rating indicates good, but not outstanding, thermal performance.
•Occupants of a 10 star home are unlikely to need any artificial cooling or heating.
Energy from the sun
• Summer sun radiation approx. 1000 watts/ m2• That’s why you want to bock it out
• Winter sun approx. 500 watts / m2• That’s why you want to let it in
Houses will be more comfortable if we make the most of what nature can offer
“It seems to me that we all look at Nature too much, and live with her too little.”Oscar Wilde, "De Profundis", 1905
Sun control begins in the garden
• The trees provide a HUGE benefit for summer cooling• Keep north windows unshaded to allow winter sun into windows• More comfortable interiors, cheaper to run
Credit: Ian Garradd
Thermal mass• Heavy, massive materials have large heat capacity. • Internally, they can retain very useful warmth, or coolth.• Exposed, i.e. not carpeted surfaces are best- i.e. tiles, brick, etc.
• Thermal mass inside a house reduces daily
temperature fluctuation
Summer
Winter
Credit: yourhome
Design features for summer comfort
Street frontage faces north, season- mid summer
• Large north facing windows with wide northern eaves• Keeps the summer sun out, but lets the winter sun in.• What effect will happen on the west windows/ wall in pm?
Roof colours
• White coloured roofing is around 30 degrees cooler than dark • Where is a large part of the heat going to end up?• Reliance on air conditioning?
Trees for cooling
1. Trees are essential for controlling temperature in and around the home
2. The yard is far more pleasant with the cooling effect of trees3. An extremely low cost solution for summer cooling 4. If tank water is available, put the sprinkler through the leaveson for free air conditioning
Image: yourhome.gov.au
Keep the sun off the glass in summer
If glass gets hot, heat is already heading inside•External shading is far better than internal shading – blinds, etc.•External shutters•External awnings•External roller blinds
East facing house
Awnings
• Best for east or west walls• Ensure a heat-reflective fabric
is specified• Leave up in winter to let
winter heat in• Needs occupant motivation
to control it• Awning should extend
beyond window frame , i.e. approx. 300 mm each side
Image: Ian Garradd
Insulated and lined verandas
• A verandah, eave, or awning with insulation transmits negligible heat.
• This will heavily impact on interior temperatures, as much of the heat which comes through as radiation goes through the walls and windows to the interior.
Image: Ian Garradd
Reflective foil insulation
2 main categories of insulation….Reflective foil is most suited to keeping heat out in summerThick blanket insulation is for keeping heat inside They are both essential for year –round comfort
• Generally put under sheeting and tiles but retrofitting easier under rafters.
• A more effective and safer method of retrofitting foil (just a bit more effort)
Night purging and breezes
Methods of achieving air movement in a house.
sealable high wall vents
roof ventilator
ceiling fan
closable inlet vent for exhaust fan
exhaust fan
fully openable window area
openings on opposite sides
of house
closable inlet vent for roof ventilator
minimal obstructions between openings
• Landscaping to direct cooling breezes
• Allow cross- ventilation to do most of the cooling with sea breezes, or night breezes
• Requires vigilance
Image: yourhome.gov.au
Be familiar with useful breezes
Wind roses showing local summer breezes at 9am and 3pmStrong afternoon cooling breezes from the East and South-East
Security screens • Security screens essential
in many cases so that people can relax while leaving doors and windows open for summer cooling.
The Stack Effect for summer cooling
• Allows warm air to leave the house by convection
• Open windows and doors in summer
• Operable skylights are also excellent for this
Image: US dept. of housing
Cross–flow for most effective cooling
• In the front door and out the back,
• Or open whatever combination of windows and doors can achieve air flow through most of the house, or warm rooms.
Whirlybirds
Exercise:200 m2 dark roof tiles….
•Calculate the load at any one time•How much difference will 1 whirlybird make?
Image: Ian GarraddImage: Nearmap.com
Maximise cooling potential for hot weather
Always use natural breezes instead of appliances to keep cool if possible
A better solution
• White roof, • Multiple industrial size whirlybirdsThis combination has a large impact on internal temperature
Image: Ian Garradd
Effective venting of warm air from interior
Operable skylights •Remove heat from ceiling level•Available with double glazing, thermal treatments, and blinds.•Highly effective and versatile
Image: Ian Garradd
Summer climate control review.
• Each person to recount an experience of an aspect of a home, where it was too hot.
• Explain what you would do about it - in hindsight• Summarise the main aspects of heat control.
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