New Importance of insulation - Nauticool · 2020. 6. 3. · 2. Reflective insulation – is used to resist radiant heat flow. This type of insulation has high refelctivity and low

THE IMPORTANCE OF INSULATIONTHE IMPORTANCE OF INSULATIONTHE IMPORTANCE OF INSULATIONTHE IMPORTANCE OF INSULATION

OUTLINE

Overview

Analysis and Discussion

Understanding Insulation � Heat transfer � Insulation types � Measurement of insulation performance � Installing Insulation � Insulation levels

BCA requirement for insulation � About BCA � The BCA 2010 insulation requirements � Climate zones in Queensland � Insulation requirements in Queensland

How to achieve 6-star requirements? Insulation strategies How to estimate the total R-value

How to ensure insulation is efficient? Summary

Energy Efficient Acceptable Construction Practice Case Study

OVERVIEW Since 2010, Queensland Government has set a 6-star energy efficiency requirements for new homes. The requirements applies to all new houses and townhouses (class 1 buildings), enclosed garages (class 10a buildings) attached to class 1 buildings and new work done on existing buildings. The energy equivalence rating of a home is determined through the design of its building shell, which refers to the roof, walls, windows and floors. The rating is out of ten stars--the more stars, the more comfortable and the higher its energy efficiency.

The standards set by the government aims to incorporate range of passive design features into the home to improve its energy efficiency and to create a more comfortable environment with less need of artificial cooling and heating. There is no single feature of a home that can maximise its thermal performance. It is always a combination of several factors. In Queensland, as stated in the Design Guide For 6-Star Energy Equivalence Housing, the key passive design principles that can be applied to a house design are as follows:

• northern orientation of living rooms

• minimising east and west facing walls

• wider eaves and awnings for shading

• natural ventilation through windows and doorways

• increased insulation in the roof space and walls

• treated glazing, particularly for windows facing west and north-west

• light coloured roof and external walls

• ceiling fans in living areas and bedrooms

• well-designed and located outdoor living areas e.g. decks, verandahs and patios.

One of the key design feature, which is the focus of this paper, is the insulation installed in the roof space and external walls of a dwelling that help achieve an energy efficient building and thermal comfort. Insulation provides a more stable internal temperature by reducing the heat and cold transfer between the home and its external elements.

ANALYSIS AND DISCUSSION

Understanding Insulation

According to Retrofitting for Sustainability Guide, a good roof insulation system is typically the most cost effective way to improve a home’s energy efficiency and could save you up to $200 each year on your electricity costs (Barrett, 2012).

Insulation serves as a barrier to heat transfer in roofs, ceilings, walls and floors. It is essential in keeping the home warm in winter and cool in summer. Well-insulated home maintains a comfortable indoor temperature all year round and minimise the need for

cooling and heating, thus, reducing electricity consumption and the greenhouse gas emissions (McGee, Mosher, DCCEE, & Clarke, 2010). Barrett further discussed that although insulation are required to newly-built homes, many older homes, up to 40% of Australia’s housing stock, remain un-insulated.

Typical heat flow in an uninsulated home during winter and summer ( Source: Sustainable Energy Authority Victoria)

Around 45-55% savings of the heating and cooling energy can be attributed to insulation. Below shows the potential savings for installing insulation to a home:

Typical energy savings due to insulation (Source: Sustainable Energy Authority Victoria)

Insulation is effective when passive design principles are applied to the home. With an unprotected glazing and insufficient ventilation, insulation can trap the heat causing oven-like effect inside the home. In conjunction with passive design, Sustainable Energy Authority Victoria enumerated the folliwing benefits that can be achieved through insulation:

• Comfort inside the home

• Reduced heating and cooling costs

• Pays for itself in around five to six years

• Eliminates condensation on walls and ceilings

• Sound proofing

Heat Transfer Insulation refers to the materials that prevents the transfer of heat. When these materials are installed appropriately to the home, the heat flow into and out of the building are reduced. Without insulation, heat can transfer easily through the roof, ceiling, walls and floors of a home in three ways:

1. Radiation – direct heat from the heat source. Ex. Sun shining through a window and directly heating the floor.

2. Convection – heat carried by the circulation of liquir or gases.

Ex. Hot air in the room rises, drawing cooler air from below.

3. Conduction – heat transfer through solid objects. Ex. Heat transferred from the outer surface of a wall to the inside surface of a wall inside the home.

Insulation types

Most common construction materials offers little insulating value except for materials like aerated concrete blocks, hollow expanded polystyrene blocks, straw bales and rendered extruded polystyrene sheets (McGee et al, 2010). Insulation must be installed for a home to comply with the Building Code of Australia (BCA) requirements for energy effiency of building fabric.

Your Home Technical Manual discussed the two main types of insulation:

1. Bulk insulation – prevents the transfer of conducted and convected heat. Materials such as glasswool, wool, cellulose fibre, polyester and polystyrene are exampls of bulk insulation. It is usually available in batts, rolls or boards. This type of insulation comes with one Material R-value for a given thickness.

(Source: Sustainable Energy Authority Victoria)

2. Reflective insulation – is used to resist radiant heat flow. This type of insulation has high refelctivity and low emissivity (ability to re-radiate heat). It is usually shiny aluminum foil laminated onto paper or plasic and is available as sheets (sarking), concertina-type batts and multi-cell batts. A still air layer (enclosed air space) of at least 25mm makes this type of insulation work most effectively.

(Source: Sustainable Energy Authority Victoria)

Some products combine the bulk and reflective insulation properties like the reflective foil faced blankets, foil backed batts and foil faced boards.

Measurement of insulation performance

The performance of the insulation material is measured by an R-value, which describes the thermal resistance of a material (i.e. how much it inhibits heat transfer). The higher the R-value number the greater its insulating effect (Queensland Department of Local Government and Planning, 2011). As discussed in the Insulation Benefits fact sheet, R-values are expressed using the metric units m2/K/W, where:

• m2 refers to one metre squared of the material of a specified thickness;

• K refers to a one degree temperature difference (Kelvin or Celsius) across the material; and

• W refers to the amount of heat flow across the material in watts. There are two ways to measure the R-value:

1. System R-value (or Total R-value) – the total thermal resistance for the sum of all the building materials as well as the insulation product, i.e. building materials + air-films + air spaces + insulation product

2. Product R-value (or Material R-value) – the thermal resistance of the

insulation product alone.

R-values differ depending on the direction of heat flow through the product. The difference is generally marginal for bulk insulation but can be pronounced for reflective insulation (McGee et al, 2010).

• Up R-values describe resistance to heat flow upwards (sometimes known as

‘winter’ R-values). • Down R-values describe resistance to heat flow downwards (sometimes known as

‘summer’ R-values).

Insulation thickness for some specific R-values:

* Rounded to the nearest 10 mm Source: CSIRO, Building, Construction & Engineering (modified), published in Choice Online

When reflective insulation is used in a roof, it must be laid directly under the roof cladding and must have a minimum air space of 15mm between the reflective side of the reflective insulation and the adjoining building lining or cladding (South Australian Housing Code). Refer to the table below for R-value added by the reflective insulation to the Total R-Value.

R-Value added to roofs by reflective insulation:

Source: South Australian Housing Code For reflective insulation used in walls, refer to the table below for the R-value added:

Source: South Australian Housing Code

Installing Insulation

The perfect and the most economical time to install insulation into your home is during the construction of the building, renovation, and re-cladding or re-plastering for wall insulation. Insulation are installed in the following:

• Under the roofing material to reduce the radiant heat

• In the ceiling installed between the joists to reduce heat gain and loss

• External walls to reduce radiant, conducted and convected heat transter (within the cavities, within stud frames, outside of stud frames, and inside or outside of solid walls)

• Floors in cool temperate and alpine climates, in some temperate climates, and in high humid and hot dry climates where air conditioning is used.

• Edge of slabs on ground in cool temperate and alpine climates and in temperate climates where slab heating is used

• Underside of slabs on ground in alpine climates and where groundwater is present

To find out if insulation have been installed, check your roof space if you can find bulk insulation, which is usually fluffy, tan or pink, and installed between the ceiling joists or as a blanked with a foil lining under the roof sheeting. Old insulation needs replacing.

Insulation levels

The degree of insulation varies per climate, building construction type, and whether auxiliary heating and/or cooling is to be used (McGee et al, 2010).

Building Code of Australia (BCA) set minimum insulation requirements for a range of locations. The table below, however, does not distinguish between directional R-values for roofs and ceilings. Hence, Your Home Technical Manual advised that for high humid climates where houses are naturally ventilated, high down values and lower up values are appropriate for roofs and ceilings.

* Note: These minimum insulation levels will be higher if your roof has an upper surface absorptance value of more than 0.4. (Source: BCA 2010 Volume Two)

Before installing insulation Queensland builders must ensure they take into account several points:

1. Climate zone 2. BCA Building Class

3. Ceiling Insulation Compensation for required increase of ceiling insulation R-value

4. BCA – Design Conditions (‘Summer’ heat flow in or ‘Winter’ heat flow out) according to the building class, climate zone, and state jurisdiction on the project.

5. Total R-value determined by the applicable roof, wall and floor systems.

Insulation installed in the roof space and external walls of a dwelling is a key design feature that can be used to assist in achieving energy efficient buildings and thermal comfort. It can reduce the heat and cold transfer between the dwelling and external elements, thereby providing a more stable internal temperature.

BCA requirement for insulation

About BCA

The data sheet on Energy Efficiency in Building Regulations and the Use of Concrete in Housing discussed that since early 1980s, Australia has shown a steady progress towards increasing energy efficiency of building envelopes. In 2003, the Australian Building Codes Board (ABCB) published amendments to the Building Code of Australia (BCA) Volume 2 with the objective of reducing energy use; hence, the greenhouse gas (GHG) emissions. Since then the BCA has been progressively amended, providing increased stringency. The building sector may not be the largest contributor of GHG emissions but it’s one of the fastest growing sources. Almost 27% of all energy related GHG emissions is attributed to buildings. The BCA provides Australia with national model for building regulations. State governments have the discretion to adopt the BCA model or not. New South Wales for instance has opted for alternative regulations (Cement Concrete & Aggregates Australia, 2011). The National Construction Code (NCC) was published in 2011. It published three volumes—Volume One pertains to Class 2 to 9 buildings, Volume Two primarily to Class 1 and 10 buildings, and Volume Three pertains primarily to plumbing and drainage associated with all classes of buildings. NCC has retained the term Building Code of Australia (BCA).

Class 1 buildings refers to a single dwelling (Class 1a) and boarding house, guest house, hostel or the like with a total area of all floors not exceeding 300 m2 (Class 1b). Class 10a buildings refer to non-habitable buildings that include private garage, carport, shed, or the like.

The BCA 2011 Insulation Requirements

Under the BCA, roof or ceiling insulation products must comply with the labelling, testing, quality assurance and other requirements of AS/NZS 4859.1: 2002 – Materials for the thermal insulation of buildings – Part 1: General criteria and technical provisions. Some imported insulation products, such as glass-wool batts and laminated foil, may not comply with this standard. Building practitioners are recommended to check that it complies with these standards by appropriate means, such as:

• Requesting a copy of a report by an accredited laboratory showing that it complies with the standard;

• Checking that labelling or manufacturing supply documentation includes a statement that it complies with the standard;

• That the labelling or manufacturing documentation declares the R-value of the product and it meets the specified R-value for the location of the building.

Climate Zones in Queensland

Four different climate zones exists in Queensland

(Source: Growth Management Queensland, 2011)

Source: Cement Concrete & Aggregates Australia, 2011 – Energy Efficiency in Building Regulations and the Use of Concrete in Housing

Due to the various climates in Queensland, house designs and specifications differ to suit the climate zones. A house designed for Cairns’ climactic conditions, for instance, is not appropriate for Toowomba (Growth Management Queensland, 2011).

Insulation requirements in Queensland The residential energy efficiency requirements in the Building Code of Australia (BCA) were introduced back in 2003. These set minimum standards, and for some years they have been equivalent to 5 stars. From 1 May 2010, 6-star energy efficiency requirements for new homes became mandatory in Queensland. The 6-star requirement applies to all new houses and townhouses (class 1 buildings), and enclosed garages (class 10a buildings)

attached to class 1 buildings. The requirement also applies to new work done on existing buildings, such as additions, alterations or re-locations. Local Governments are required to ensure that building applications comply with the design requirements of the BCA before granting building approval. Building service practitioners must then ensure that building work is carried out in accordance with the technical provisions of the BCA, as approved by the Local Government. The Queensland government has adopted the energy efficiency measures of the BCA 2011 Volume 2 into the state building regulations (Cement Concrete & Aggregates Australia, 2011). In Queensland, the Queensland Development Code (QDC) and the Building Code of Australia (BCA) provide the relevant building assessment provisions for building works and apply to all local government areas throughout the state. As a non mandatory practice, a building certifier would request a Building Form 15 (Compliance Certificate for Building Design or Specification under the Building Regulation 2006), which confirms that the building’s design and lighting configuration are in compliance. The building shell—the roof, walls, windows and floors—is the basis for the energy equivalence rating. The rating is up to 10 stars. The more stars a home has, the more energy efficient and comfortable it is. The design standards aim to use a range of passive design features, which includes increasing insulation in the roof space and walls.

Below is the roof and ceiling minimum Total R-value requirements from BCA—BCA 2011 Volume 2 Table 3.12.1.1—presenting an increased stringency with Total R-value depending on roof colour.

Note: Altitude means the height above the Australian datum at the location where the building is to be constructed (Source: Cement Concrete & Aggregates Australia, 2011)

In climate zones 1, 2, 3 and 5, the required Total R-Value specified above may be reduced by 0.5, provided the required insulation is laid on the ceiling; and the roof space is ventilated as specified in BCA (Cement Concrete & Aggregates Australia, 2011).

Solar absorptance is the measure of the proportion of solar radiation absorb by an object. The higher the solar absorptance, the more energy will be absorbed. Absorbed energy is emitted by radiation and convection from all surfaces (Roofing Tile Association of Australia, 2011) Typical absorptance values:

Therefore, based on the BCA requirements for roofing, the following colours are appropriate to meet the minimum Total R-Values:

• For Minimum Total R-Values of 4.1: off white and light cream

• For Minimum Total R-Values of 4.6: light grey, galvanized steel, zinc aluminium, and yellow

• For Minimum Total R-Values of 5.1: red, green, and dark grey Utilizing light colours and smooth surfaces is great for warmer climates because it reflect heat away from home. Darker colours and rough materials are more appropriate in cooler climates because it absorb heat (Queensland Department of Housing and Public Works).

External walls – the required R-values fo climate zones 1, 2, 3 and 5 has been increased to R2.8 or R2.4 if walls are shaded.

Floors – the table below shows the minimum Total R-Value for suspended concrete floors:

(Source: Cement Concrete & Aggregates Australia, 2011)

The Energy Efficiency in Building Regulations and the Use of Concrete in Housing further discussed that suspended concrete slab construction with in-slab heating or cooling system must have insulation with an R-Value of not less than 1.0 installed around the edges. For situations that sections of ceiling cannot be insulated because of recessed down lights, exhaust fans, etc, the loss of insulation must be appropriately insulated using the table below:

Source: Martini Industries Pty Ltd, 2011

How to achieve 6-star requirements? To achieve a 6-star rating all class 1 buildings and attached 10a buildings in Queensland are required to comply with the BCA requirements part 3.12 and the Mandatory Part (MP) 4.1 Sustainable Buildings in the Queensland Development Code (QDC). MP 4.1 sets out four different methods for a new home to achieve 6-stars taking into account the BCA requirements and Queensland’s unique climate which spans four climate zones.

Option 1: Complying with BCA 2010 elemental provisions (previously known as Deemed to Satisfy) as per Part 3.12 – Energy efficiency in Volume 2 (with specific variations outlined in Queensland Development Code 4.1) will give a ‘deemed’ 6-star rating without any additional inclusions or offsets. These provisions include: roof/ceiling, external walls, floors, external glazing, building sealing, and air movement.

Option 2: Modelling a building through one of the three design software – BERS Pro, FirstRate 5 or AccuRate, and performed by a house energy assessor. Where the software assessment method is used building certifiers must ensure that the requirements of Section 3.12.0 of the BCA, including the installation of insulation, thermal breaks and building sealing, are incorporated with the building’s design. Option 3: Verification – using a reference building that allows the intended design to be compared with the design that is known to comply. Option 4: Peer review – having an expert review and advise on house designs that may not readily comply with the above compliance methods.

Insulation Strategies

Due to various climate zones in Queensland, appropriate insulation is advised. Zone 1 – Tropical

Temperature: very hot summers Humidity: very high humidity in summer Rainfall: very high rainfall in summer Insulation:

- Choose a reflective insulation for both roof and walls to reduce the amount of heat transfer.

- Air conditioned home should use bulk insulation, mass materials and double glazing to improve energy efficiency.

Zone 2 – Subtropical

Temperature: hot summers Humidity: high humidity in summer Rainfall: ideal breezes Insulation:

- Light coloured roofing materials with reflective foil insulation protects the home from heat transfer during the hot summer months and maintains warmth during winter.

Zone 3 – Hot arid

Temperature: very hot summers and cold winters Rainfall: low rainfall all year Breezes: dry winds all year round Insulation:

- Using bulk insulation within the light weight construction and heavy weight construction protects the home from heat gain in summer and heat loss in winter and provide good thermal comfort all year round.

Zone 5 – Warm temperate

Temperature: very cold winters Humidity: high humidity Breezes: needs protection all year round Insulation:

- The use of bulk reflective insulation will help preserve the internal temperatures in winter and summer.

How to estimate the total R-value • Find the construction type that relates to your situation (e.g. pitched tiled roof

with a flat ceiling and an unventilated roof space). Calculate the total thermal resistance of the building components of your construction type.

• Add the material R-value of insulation you are installing. This will give you an approximate total R-value.

For example, adding bulk insulation with a material R-value of 2.5 will increase both the up and down total R-values by around 2.5, as long as the material is not compressed. Adding reflective insulation with a system R-value of 1.7 up, 3.0 down will increase the total up and down R-values by those amounts, providing the insulation is installed as specified with air gaps.

This method provides a useful estimate, but it must be noted that many factors (like thermal bridging, compression of bulk insulation, dust settling on reflective insulation, and the lack of a suitable air gap for reflective surfaces) can reduce the total R-value and you will need to compensate.

How to ensure insulation is efficient?

The Insulation Council of Australia and New Zealand (ICANZ), which members provide approximately 70% of insulation sold in Australia and New Zealand, has developed a detailed set of measures to improve the energy efficiency of the roof space according to its structure.

The main purpose of ICANZ recommendations is to give builders and house owners ideas and guidelines how to ensure efficiency of insulation while keeping the BCA requirements for R-Value of insulation products and Total R-Value of a space insulated.

Energy Efficient Insulation Options:

Roof Type Uninsulated Structure Insulation installation

Pitched tiled roof with flat ceiling

Pitched tiled roof between 18o and 35o, 40mm battens, attic space, 10mm plasterboard flat ceiling.

� Reflective insulation shall be draped under 40mm battens, antiglare side facing outwards. When used as sarking, reflective insulation, foil shall have 150mm overlap in accordance with AS/NZS 4200.2.

� To maintain effectiveness as insulation or sarking, any tears or gaps shall be repaired with a suitable reflective foil tape.

� R3.5 ceiling batts positioned between joists on ceiling lining.

Pitched metal roof with flat ceiling

Pitched metal roof between 18o and 35o, 40mm battens, attic space, 10mm plasterboard flat ceiling.

� Foil faced blanket shall be installed with foil facing attic space with the blanket compressed over battens. Blanket must be allowed to recover to its full thickness.

� AS 3959 “Bushfire Standard” requires that all sarking products must be installed under the batten, else reflective insulation may be draped over battens to create a 40mm air space, antiglare side facing outwards.

� All joins in foil should be lapped 150mm.

� To maintain the effectiveness of the insulation membrane, any tears or gaps shall be repaired with a suitable reflective foil tape.

� R3.5 ceiling batts positioned between joists on ceiling lining.

Pitched tiled roof with cathedral ceiling below rafters (concealed rafters)

Pitched tiled roof between 18o and 35o, 40mm battens, 190mm deep rafters, ceiling battens, 10mm plasterboard.

� Reflective insulation draped beneath 40mm battens to create a 40mm air space. All joins should be lapped 150mm in accordance with AS/NZS 4200.2.

� To maintain the effectiveness of the insulation membrane, any tears or gaps shall be repaired with a suitable reflective foil tape.

� Where insulation batts (eg. R3.0) are incorporated in the structure a 25mm reflective air space is maintained between the lower side of the foil and the batts.

� Where there are no ceiling batts, the airspace below the sarking will be approximately 190mm.

Metal roof with cathedral ceiling below rafters (concealed rafters)

Pitched metal roof between 18o and 35o, with 40mm battens, 190mm deep rafters, ceiling battens with 10mm plasterboard fixed below.

� Foil faced blanket shall be installed with foil facing attic space with the blanket compressed over battens. Blanket must be allowed to recover to its full thickness.

� AS 3959 “Bushfire Standard” requires that all sarking products must be installed under the batten, else reflective insulation may be draped over battens to create a 40mm air space, antiglare side facing outwards.

� All joins in foil should be lapped 150mm.

� To maintain the effectiveness of the insulation membrane, any tears or gaps shall be repaired with a suitable reflective foil tape.

� Where insulation batts (eg R3.0) are incorporated in the structure a 25mm reflective air space is maintained between the lower side of the foil and the batts.

Tiled roof with cathedral ceiling above rafters (exposed rafters)

Pitched tiled roof between 18o and 35o, 40mm battens, 190mm deep rafters, counter batten to provide minimum 70mm air space, 10mm plasterboard ceiling fixed mid-way up exposed rafter.

Option 1: Single sided polyweave foil positioned over batten with 30mm reflective EPS board positioned at mid height of 70mm air space providing 20mm air space above and below.

Option 2: Single sided polyweave foil positioned over batten. Original 70mm air space below single sided polyweave foil replaced with 20mm air space and R1.5 - 50mm bulk insulation on the ceiling lining.

Metal roof with cathedral ceiling above rafters (exposed rafters)

Pitched metal roof between 18o and 35o, 110mm battens, rafters, 10mm plasterboard ceiling fixed at top of exposed rafter.

Option 1: R1.8 foil faced blanket draped over battens.

The following options may be governed by AS 3959 “Bushfire Standard” which requires that all sarking products must be installed under the batten.

Option 2: In non-bushfire areas reflective insulation may be draped over battens to create a 40mm air space, antiglare side facing outwards. All joins in foil should be lapped 150mm. Remaining 70mm air space replaced with 20mm air space and R1.5 - 50mm, bulk insulation. Bulk

insulation positioned on 10mm plasterboard ceiling fixed between batten and exposed roof rafter.

Option 3: In non-bushfire areas, Double sided antiglare foil draped with 40mm sag over 110mm batten. Reflective 30mm thick EPS board positioned at mid height of remaining 70mm air space providing 20mm air space above and below.

Option 4: In non-bushfire areas, Polyweave or double sided antiglare, or bubble/foam foil draped over 90mm batten. (40mm air space above, 50mm air space below).

Flat metal roof with plasterboard ceiling

Flat metal roof between 0o and 5o pitch, roof battens, rafter sized to allow minimum 190mm air space, ceiling battens, 10mm plasterboard.

Option 1: R1.3 foil faced blanket draped over battens to allow full blanket thickness recovery, minimum 25mm airspace to top of R3.0 batts positioned between rafters on ceiling lining.

The following options may be governed by AS 3959 “Bushfire Standard” which requires that all sarking products must be installed under the batten.

Option 2: Double sided antiglare foil draped over battens to provide 40mm airspace above. R3.0 batts positioned between rafters on ceiling lining with 25mm airspace to underside of foil.

Option 3: Double sided antiglare foil draped over battens to provide 40mm airspace above. 30mm thick EPS board located at mid height of rafter providing 80mm air space above and below.

Option 4: Polyweave or double sided antiglare or bubble/foam foil draped to provide 40mm airspace above (bright side of foil facing down).

Flat metal roof with plasterboard ceiling (exposed rafters)

Flat metal roof between 0o and 5o pitch, minimum 110mm high roof battens, located over rafter, 10mm plasterboard located over exposed rafter.

Option 1: R1.8 foil faced blanket draped over battens to allow full blanket thickness recovery, minimum 25mm airspace to top of ceiling lining.

The following options may be governed by AS 3959 “Bushfire Standard” which requires that all sarking products must be installed under the batten.

Option 2: Double sided antiglare foil draped over battens to provide 40mm airspace above. R1.5 (50mm) batts positioned between rafters on ceiling lining with 25mm airspace to underside of foil.

Option 3: Double sided antiglare foil draped over battens to provide 40mm airspace above. 30mm thick EPS board located at mid height of rafter providing 20mm air space above and below.

Option 4: Polyweave or double sided antiglare or bubble/foam foil draped to provide 40mm airspace above (bright side of foil facing down).

Flat metal roof with no ceiling – warehouse

Flat metal roof at 0o to 5o pitch, safety mesh, purlin.

Option 1: Foil faced blanket R2.5 laid over safety mesh*, blanket allowed to recover to its nominal thickness by providing a suitable spacer. Foil side of blanket should face into the air space below.

Option 2: Double sided antiglare foil, bubble/foam foil laid on tight safety mesh without spacers, hence no airspace on top of the material and no R-value contribution from any air space.

Alternatively a spacer must be provided as per air space dimensions nominated.

Flat metal roof with suspended ceiling

Flat metal roof at 0o to 5o pitch with safety mesh over purlins. Suspended ceiling system forming 100-600mm non-ventilated airspace, 10mm plasterboard.

Option 1: Foil faced blanket (R1.3, R1.8, or R2.5) laid over safety mesh*, blanket allowed to recover to its nominal thickness by providing a suitable spacer. Foil side of blanket should face into the air space below. R2.5 ceiling batt positioned on ceiling lining.

Option 2: Double sided antiglare foil, bubble/foam foil laid on tight safety mesh without spacers, hence no airspace on top of the material and no R-value contribution from any air space.

Alternatively a spacer must be provided as per air space dimensions nominated.

Flat metal roof with suspended ceiling plenum return

Flat metal roof at 0o to 5o pitch with safety mesh over purlins. Suspended ceiling system forming 100-600mm ventilated airspace (used as a return air plenum), 10mm plasterboard.

Option 1: Foil faced blanket (R1.3, R1.8, or R2.5) laid over safety mesh*, blanket allowed to recover to its nominal thickness by providing a suitable spacer. Foil side of blanket should face into the air space below. R2.5 ceiling batt positioned on ceiling lining for acoustic benefits only.

Option 2: Double sided antiglare foil, bubble/foam foil laid on tight safety mesh * without spacers, hence no airspace on top of the material and no R-value contribution from any air space.

Alternatively a spacer must be provided as per air space dimensions nominated.

Flat concrete roof with suspended ceiling

150mm concrete slab with exterior waterproofing membrane. Suspended ceiling system forming 100-600mm non-ventilated airspace, 10mm plasterboard.

Option 1: Foil faced sheet or blanket (R1.3, R1.8, or R2.5) pinned to underside of concrete slab allowed to recover to its nominal thickness. Foil side should face into the air space below. R2.5 ceiling batt positioned on ceiling lining.

Option 2: Foil faced sheet or blanket (R1.3, R1.8, or R2.5) pinned to underside of concrete

slab allowed to recover to its nominal thickness. Foil side should face into the air space below.

Flat concrete roof with suspended ceiling plenum return

150mm concrete slab with exterior waterproofing membrane. Suspended ceiling system forming 100-600mm ventilated airspace (used as a return air plenum), 10mm plasterboard.

Option 1: Foil faced sheet or blanket (R1.3, R1.8, or R2.5) pinned to underside of concrete slab allowed to recover to its nominal thickness.

Foil side should face into the air space below. R2.5 ceiling batt positioned on ceiling lining.

Option 2: Foil faced sheet or blanket (R1.3, R1.8, or R2.5) pinned to underside of concrete slab allowed to recover to its nominal thickness.

Foil side should face into the air space below.

SUMMARY

Energy Efficient Acceptable Construction Practice

Cement Concrete & Aggregates Australia presents the Energy Efficient Acceptable Construction Practice specifically for Queensland that summarizes the required Total R-value of the building fabric—roof, external walls, suspended concrete floor and concrete slab-on-ground—that builders should be compliant and homeowners should be aware of.

Source: Cement Concrete & Aggregates Australia, 2011

Case Study

The Design Guide For 6-Star Energy Equivalence Housing presented this case study on a home design located in climate zone 2. Climate zone 2 in Queensland is characterized by its warm humid summers and mild winters. The objective of the home design is to have an interior that is cool in summer and provide warmth for winter. The house is located near the coastline to take advantage of the views.

For this design, lifestyle issues were considered within the context of the home’s location, especially the eastern location of the outdoor living area. Designers will want to provide a bright open holiday style interior, provide views to the coast and capture the cooling sea breezes in summer. For this case study, the compliance option chosen were as follows:

• Elemental (BCA 2009) plus QDC optional credits (5 stars + 1 star for outdoor living area with ceiling fan).

• The software report indicated that the base design achieved satisfactory results for cooling during summer. It did not achieve satisfactory results for heating during winter. The design was adjusted to improve solar access to the kitchen/family room and bedroom 1.

• The outdoor living area was changed to allow morning winter sun through the kitchen window.

• This option provided compliance at a lower cost than software, maintained the design’s integrity, had minimal impact on the local natural environment, provided good natural light and ventilation and would not reduce the occupant’s access to coastal views.

As a result, the home design requires the following changes to achieve 6-star compliance:

• alter the layout of the eastern outdoor living area and include a ceiling fan (additional ½-star credit)

• adjust the northern, eastern and western eaves and shading to allow sun access during winter (while maintaining summer shading)

• increase the roof/ceiling insulation to achieve a total value of R-2.7

• increase the wall insulation to achieve a total value of R-1.9

• change to a medium colour roof.

REFERENCE LIST McGee. Mosher, DCCEE, & Clarke (2010). Insulation. Your Home Technical Manual. Retrieved from http://www.yourhome.gov.au/technical/fs47.html Sustainable Energy Authority Victoria. Insulation Benefits. Sustainability Victoria. Retrieved from http://www.sustainability.vic.gov.au/resources/documents/Insulation_benefits.pdf Planning Services Special Projects Unit. Building Materials and Insulation for Townsville Homes. Townsville City Council. Retrieved from http://www.townsville.qld.gov.au/resident/planning/sustainable/Documents/Sustainable%20Housing%20Guide%205.pdf Growth Management Queensland (2011). Design guide for 6-star energy equivalence housing. Queensland Department of State Development, Infrastructure and Planning. Retrieved from http://www.dsdip.qld.gov.au/resources/guideline/six-star-design-guideline.pdf Barrett, S. (2012). Retrofitting for Sustainability, A Guide for Far North Queensland. Cairns and Far North Queensland Environment Centre. Retrieved from http://cafnec.org.au/download/publications/Retrofitting%20Guide_Final.pdf

Cement Concrete & Aggregates Australia (2011). Energy Efficiency in Building Regulations and the Use of Concrete in Housing. Cement Concrete & Aggregates Australia. Retrieved from http://www.concrete.net.au/publications/pdf/EnergyEfficiency.pdf Fong, T. (2010). Home Insulation Buying Guide. Choice. Retrieved from http://www.choice.com.au/reviews-and-tests/household/heating-and-cooling/home-heating/home-insulation-buying-guide/page/r-value-what-is-it.aspx South Australian Housing Code Appendices. Government of South Australia. Retrieved from http://sa.gov.au/upload/franchise/Housing,%20property%20and%20land/PLG/New_homes_and_extensions_prescriptive_technical_requirments.pdf Growth Management Queensland (2011). Queensland Development Code Mandatory Part 4.1—Sustainable buildings guideline. Queensland Department of State Development, Infrastructure and Planning. Retrieved from http://www.dsdip.qld.gov.au/resources/guideline/qdc-4-1-sustainable-buildings-guideline.pdf Smart and Sustainable Home Design. Designing for Queensland’s climate. Queensland Department of Housing and Public Works. Retrieved from http://www.hpw.qld.gov.au/SiteCollectionDocuments/SmartDesignQldClimate.pdf Roofing Tile Association of Australia (2011). Solar Absorptance and energy efficiency. The Australian Building Codes Board. Retrieved from http://www.abcb.gov.au/education-events-resources/national-conference/~/media/Files/Download%20Documents/Marketing%20Docs/BAF/Tanner%20%20RTAA%20BAF%202011%20presentation.ashx Martini Industries Pty Ltd (2011). Thermal Design Guide. Polymax http://www.polymaxinsulation.com.au/downloads/Polymax_Thermal_Design_Guide.pdf