Eco Priority Guide: High Performance Glazing Selection

Transcription

1 Eco Priority Guide: High Performance Glazing Selection 1.0 Overview Glass selection is one of the most important issues in building design as windows are one of largest heat gain and loss pathways in buildings. However, with over 286,000 different varieties of glass 1 (although not all of these are suitable for building use), choosing the right glass for any task can be quite daunting. While some types of glass are available in different formats e.g. float, laminated or toughened, some types are limited to specific formats e.g. spectrally selective sputter coat metalised coatings are only available within sealed insulated glass units (IGUs). The various types of glass available have expanded rapidly in recent years, but generally fall into a number of key categories: Window: o Clear o Tinted (reflective or heat absorbing) o Spectrally selective ( clear or tinted) o Specialist glasses (e.g. self cleaning or electrically switched ) Cladding: Coloured Ceramic Glasses From a sustainability point of view, the glasses that provide specific benefits (in particular thermal energy efficiency or operational energy benefits) are: tinted, spectrally selective and self cleaning. This note deals only with window glass. The FAQ section below provides more detailed information. All glass is recyclable as a commercially valuable product in fact Pilkington s patterned glass is 95% recycled. Window glass and alkali glass in general is recycled into fibreglass insulation or powdered for use as filler in paint and roads. Imported mirrors may have lead based paint backing. 2.0 Eco Priorities Glazing Selection The major general eco-priorities for glazing selection across the category are: 1. GHG emissions operational energy efficiency 2. Life-cycle self cleaning glass benefits 3. Resources source of raw materials, recyclability and recycled content Eco Priorities as they relate to specific glass types: The following issues relate to both potential positive and negative issues associated with each product class. Some items listed under single categories might also be relevant to others: Eco Priority Guide: Smart Glazing Selection: Ecospecifier 2015 Page 1 of 15

2 Priority Order Clear Toned Patterned Glass Spectrally Selective Incl. Low E Self cleaning Double glazed 1 GHG GHG (operation) Key: + Denotes issue has positive outcomes GHG+ (embodied) GHG+ (operational) Life-cycle+ GHG+ 2 Resource Resource Resource+ Resources Resources Resources 3 4 Issues of concern? Minor: Fluorine based compounds 3.0 Glass Selection FAQs 3.1 What common formats of architectural glass are available? Most architectural glasses are alkali, alkaline earth and silicate glasses. Such glasses contain about 15% alkali (usually Na 2 O); 13 16% alkaline earths (CaO + MgO); 0 2% Al 2 O 3, and about 71% SiO 2. Variants of the basic composition can also contain significant amounts of BaO with reduced alkali and alkaline earth content. These glasses can have special high temperature or chemical resistance e.g Pyran, a fire resistant glass 2. Float: is a standard commercial glass cast on a bed of molten tin. As a result, one face is slightly softer due to a small residual tin content that also makes it easier to silver for mirror production. Laminated glass: is a safety glass with thin sheets of float glass held together by an interlayer, typically of Polyvinyl Butyral (or PVB). The PVB prevents the glass from breaking up into large sharp pieces; gives the glass a much higher sound insulation rating, due to the damping effect, and blocks 99% of transmitted UV light. However, the laminated glass does not provide significant thermal benefits over and above normal float glass. Laminated glass is only suitable for limited structural purposes in 2 layers but up to ballistic grade with multiple laminations and different interlayer materials 3. Toughened glass: is a safety float glass that is reheated and then quenched at a particular temperature to recrystalize the glass. Toughened glass is also suitable for structural purposes. Double Glazing: comprises two panes of glass with a sealed space between them. The space is filled with air or an inert gas such as argon. Double glazing is sometimes called insulated glazing units (IGUs). 3.2 What is the thermal effect of the various types of glass? Clear glass: As the most basic form of glass, single sheet clear glass is preferred thermally as a single pane in only temperate climates where spaces are not air conditioned. Otherwise careful thermal design will generally favour one of the more high performance derivations. The various types of clear glass are used as the base delivery formats for the various smart glass options considered below. Eco Priority Guide: Smart Glazing Selection: Ecospecifier 2015 Page 2 of 15

3 Toned glass: is derived from additions to the body of the glass mix or from specially designed coatings, often based on metallic oxides. One of the benefits of body toned glass is that body tinting allows a percentage of recycled glass or glass impurities that usually are removed, increasing the embodied energy of clear glasses by comparison. These impurities in tinted glass assist the tinting process but do not otherwise affect the structural or optical characteristics of the glass. Where body tinted glasses are used or heat is absorbed into glass, re-radiation of the heat back into the building can be a significant negative influence on occupant thermal comfort (see below). The basic tones, are usually grey, blue and green. Super tones offer a higher level of performance, such as EverGreen and SuperGrey 4. Glass type Single Glazing Daylight % Solar Trans % (Tsv) U value SHGC Clear Float Optifloat SuperGrey Arctic Blue Ever Green Reflective Glazing Suncool SS22 on Clear Suncool SS22 on Green Suncool SS22 on Grey Monolithic Low E Products Energy Advantage Solar E (Solar Control Low E) Neutral Solar E Plus (Solar Control Low E) Neutral Clear Standard Green Grey Blue Double Glazing Clear Float (3/12/3) Energy Advantage (Surface ) 3/12/4 (EA) Solar E (Surface 2 4 (SolarE)/12/3 SunCool HP 6/12/ Table 1: Thermal properties of selected tinted glazing types 4 Eco Priority Guide: Smart Glazing Selection: Ecospecifier 2015 Page 3 of 15

4 Table 1 above shows typical values of daylight transmission, SHGC, SC and U values for different types of glass as available. Reflective coatings: can be applied to new and existing windows. They tend to stop greater amounts of heat gain than some toned glass. They also increase privacy by reducing vision. However, at night the direction of reflectivity reverses and it is reflective on the inside. In warmer climates it is important to limit heat gain through windows in summer. The use of reflective films can allow the use of larger window areas for taking advantage of views, without compromising summer performance as much as clear glazing. Strategic use of reflective films on east and west windows can improve the summer performance by reducing solar gain. This can avoid the detrimental effects that reflective films have on the winter performance of north windows; although useful solar gains in winter will also be reduced. Reflective windows should not be used where the reflected light can cause nuisance glare. Spectrally selective glazing: maximises light transmission while simultaneously reflecting unwanted solar radiation (UV and near infrared). Spectrally selective coatings can also have low emissivity. Low-emissivity (Low E) coatings are microscopically thin, virtually invisible, metal or metallic oxide layers deposited on a window or skylight glazing surface primarily to reduce the U-factor by suppressing radiative heat flow. The principal mechanism of heat transfer in multilayer glazing is thermal radiation from warm surfaces to cooler surfaces. Low E coatings also reduce light transmittance by about 10% compared to clear glass. When the low emissivity coating is deposited onto the surface of the glass during the manufacturing process it is referred to as pyrolitic or hard coat Low E. There are two types of Low E coating: Hard coat Low E is less susceptible to handling damage and can be easily processed after manufacture. In cold climates it is best used in position 3 in clear Insulated Glass Units (IGUs) to allow solar heat gain and insulate against heat loss. It can be also be used with the Low E coating exposed to internal air, (i.e. position 2 or 4). As all glazing relies on the internal air film, care must be taken when positioning central heating or air conditioning outlets to restrict the amount of additional air movement over the glass. When the Low E coating is applied after manufacture, normally in a vacuum vessel, it is referred to as a sputter or soft coat Low E. Care must be taken to ensure that, when handling soft coat Low E after manufacture, they are only used in position 2 or 3 in insulated glass units (IGUs). There is also now an increasing range of ultra high performance glasses that combine various tints, Low E and other spectrally selective characteristics these are useful where solar control and natural lighting are a priority 5. Low E Coating performance: is now generally taken to refer to coatings with an emissivity less than 0.2. With one of the glass surfaces having a coating with emissivity less than 0.2 (compared with 0.84 for the uncoated glass surface), the radiation exchange is reduced by approximately 75% and consequently the U-value is reduced. At ambient temperatures, the long wave radiation lies between 5,000 50,000nm where the reflection of Low E coating is high extending beyond the wavelength coordinate. The development of hard, low emissivity coatings widens the possibility of including coated monolithic glazing in secondary frames applied to existing windows; the earlier, softer Low emissivity coatings were restricted to protected use in sealed glazed units only. Eco Priority Guide: Smart Glazing Selection: Ecospecifier 2015 Page 4 of 15

5 The present technology of on-line, hard Low E coatings can provide slightly higher solar heat transmission than that exhibited by soft coatings, giving improvements to passive solar gain applications. In cold climates, the higher temperature of the inner glass surface of double glazed units using Low E coatings diminishes the effect of colder long wave radiation causing discomfort near the window. Water on the coated surface of the glass, perhaps as a result of condensation, will cancel out the effect of the Low E coating because of the high emissivity of water 6. Energy Advantage Low-E TM : is a clear glass glazing with a transparent coat of Flourine doped Tinoxide. It was developed to reduce heat loss and improve insulation for window applications in cooler climates. The glazing product has a coating that allows short wavelength energy (daylight) from the sun to pass into the house, but reduces the amount of long wave radiation (infrared heat) that escapes through the window. The Energy Advantage technique has formerly only been available as a soft coat in double glazing. The new Energy Advantage glazing uses a hard coat that can be applied on single glazing. Solar E TM Solar control Low-E: is a hard, neutral-coloured, pyrolitic coating on clear glass with properties similar to Energy Advantage. The glazing gives an improved solar and thermal insulation. It was designed for window applications in warmer climates to reduce the warmth (long-wave radiation) of the sun entering residential buildings while still allowing transparency of visible light (short-wave radiation). Solar E limits solar heat gain by blocking passage of infrared and some ultraviolet rays. Double Glazing: offers a much better insulation than single glazing. The space can be filled with air or an inert gas such as argon with much better insulating properties than glass. The best thermal performance for air-filled units occurs when the space between the panes is about 12mm. All treated glass must be used with caution and properly considered in building thermal design as performance glass can reduce heat gain and daylight in winter as well as summer and the higher the summer performance, the more marked this effect can be in winter, depending on whether the heat loads in the building under consideration are internal load dominated or climate dominated. 3.3 What other sustainability benefits arise from different glass types? Self cleaning: is available on a variety of glass types (such as Viridian). It comprises a 50nm coating of titanium dioxide on the outer surface of glass and introduces two mechanisms which lead to the self-cleaning property. The first is a photo-catalytic effect, in which ultra-violet rays catalyse the breakdown of organic compounds on the window surface. The second is a hydrophilic effect in which water is attracted to the surface of the glass, forming a thin sheet which washes away the broken-down organic compounds How can I tell which is the best glass to use? There are a variety of indicators to determine the most efficient glass to use for specific purposes once you are aware of the performance requirements needed for the design and climate. Eco Priority Guide: Smart Glazing Selection: Ecospecifier 2015 Page 5 of 15

6 3.4.1 U-Value, Solar Heat Gain Co-efficient (SHGC) and Visual Light Transmission U-Value: is the overall heat transmittance or heat transfer coefficient measured in W/m 2 C. It represents the reciprocal of the equivalent total thermal resistance and is calculated from air to air, like the overall R- value. Quoted U-values are for still air conditions indoors and low wind speed conditions outdoors. Any high air movement over the surface, such as breezes, will significantly reduce the effective U-value. When considered in context with windows, the whole-window U-value (Uw) is used, accounting for the performance of the frame, edge-of-glass and centre-of-glass components (as used by WERS see below) 5. timber frame 3.1 aluminium frame with break 3.8 aluminium frame 12.7 single pane glass 4.7 double glazing 3.0 low E double glazing 2.2 glass and curtain 4.1 glass drapes and pelmet 1.8 R 1.0 wall element 0.9 Figure 1: U-value of Common window elements 5 Heat transmittance through glazing elements. Solar Heat Gain Coefficient: represents the performance of a window with respect to solar radiation driven heat flow. The SHGC is a measure of how much radiation will enter the space through the glazing compared to the total amount of radiation striking the glazing at an angle of incidence of 0. Because all glazing stops some radiation entry the practical upper limit of the SHGC is 0.87 i.e. the SHGC of single clear glass. For a number of years the Shading Coefficient (SC) was used to describe the solar radiation performance of glazing. This is similar to the SHGC except that it is the ratio of how much radiation is admitted compared to single clear glass. It has an upper limit of 1.0. The SHGC is now the preferred measure; however, energy assessors may see old trade literature or text books refer to the SC 4. Whole-window solar heat gain coefficient (SHGCw) as used by WERS (see below) accounts for the performance of the frame and glass components. With SHGC, there is no distinction between centre-of-glass and edge-of-glass 8. Glass Visible Light Transmittance: is the factor derived from the percentage of visible light transmitted through the glazing under a standard sky, with 100 being clear glass and 0 being obscure. The whole-window visible transmittance used in WERS (see also below) (Tvis) is a product of glazing and glazing/frame area ratio The Window Energy Rating Scheme (WERS) ANAC vs NFRC Developed by the Australian Window Association and the Australian Greenhouse Office, WERS rates the energy performance of windows, skylights and applied window films. Originally only rating residential windows and mainly aluminium, it now covers both commercial and residential as well as all frame types, skylights and window films. It is an accredited scheme that is based on close and continuing collaboration with the evolving energy-rating systems developed internationally by the United States National Fenestration Research Council (NFRC). Eco Priority Guide: Smart Glazing Selection: Ecospecifier 2015 Page 6 of 15

7 The concept is similar to that used for household appliances. The 5 star rating range is based on the relative, whole-house energy improvement caused by the use of a given window compared with using the base-case product of a single-glazed clear aluminium frame. They are based on a broad range of generic windows chosen to represent actual products on the Australian market. The WERS scheme operates on three levels to convey information about the energy performance of custom-rated windows and skylights Star ratings for heating and cooling Indicative % reduction in heating and cooling needs and interior fading damage Thermal, solar and optical performance data Most of the rating data produced by WERS is at the level of the manufactured product and is therefore valid regardless of the final building type in which the product is employed. Only the WERS star ratings are building-specific and relate to the annual energy impact of the rated product on a model house. All other WERS rating data is application-independent and can be adjusted and customised for any building type, usage pattern or climate 8. For the period two energy rating results for windows are required and will be available from WERS. Results in ANAC (Australian National Average Conditions) are required for use with first generation HERS (House Energy Rating Software). Results in NFRC-100 (National Fenestration Rating Council) environmental conditions are required for use with second generation HERS. WERS is finalising re-rating its entire database to the new protocols and procedures of NFRC rating required under the Energy Efficiency provisions of the BCA 2006 and is expected to be launched by September 2007 and be formally available for all second generation residential simulation tools (AccuRate, BERS Pro and First Rate 5) by October 2007 ready for the introduction of BCA 2008 when all States will require minimum 5 Star energy performance. WERS conforms to the alternative solution path for energy efficiency within the Building Code of Australia Fenestration energy council established In January 2007 the Australian fenestration industry committed to providing unified energy solutions through the establishment of the Australian Fenestration Rating Council (AFRC) and confirming Australia s membership to the international NFRC, the National Fenestration Rating Council. The AFRC will administer uniform, independent rating and labelling systems for the energy performance of windows, doors, skylights and attachment products 7. The AFRC is modelled on successful fenestration councils already well established in the UK and America and others in discussion about forming Councils include India and China. If implemented, it would lead to a single international rating scheme in those countries because the NFRC test conditions are uniform and assessors are internationally certified and audited using similar protocols to NATA and ISO 9000 and procedures ARUP & Australian Glass & Glazing Manufacturers Association (AGGA) Toolbox The Glass and Window ToolBox was the first tool that allows you to easily compare the energy performance of diverse glass and framing combinations to determine the right glass type to achieve a specified performance level for the façade or window system. The ToolBox generated window and glass schedules that could be used in specifications and to communicate with suppliers when you need to check availability and cost. The toolbox however does not assess windows to the NFRC protocols adopted by the AFRC and a review process is complete, the window registration and Eco Priority Guide: Smart Glazing Selection: Ecospecifier 2015 Page 7 of 15

8 kg CO2 eq per household certification facility of the Glass and Window ToolBox client/server system is not available. In the meantime the Glass and Window ToolBox continues to provide an invaluable modelling and design tool for anyone seeking to identify and source glazing and framing options Can I use high performance glass instead of external shading? High performance glass can dramatically reduce heat loads in buildings. However, recent experiences in major office and residential towers in one of Australia s iconic new green development precincts has shown that avoiding the use of external shading and opting for tinted high performance glass instead has lead to major heat discomfort for occupants that is likely to lead to major legal ramifications. The reality of exposed glazing (particularly heat absorbing glazing) is that, as efficient as it is, (see Figures 2-4 below), when the sun shines directly onto glass, it heats up and can become a major heat source in its own right, re-radiating the absorbed heat into the internal spaces and increasing the mean radiant temperature Brisbane SG Brisbane DG Sydney SG Sydney DG Canberra SG Canberra DG Melbourne SG Figure 2: Greenhouse gas emissions savings from coated glass substitution in residential building expressed in kgs of CO2 equivalents per household 11 Eco Priority Guide: Smart Glazing Selection: Ecospecifier 2015 Page 8 of 15

9 kg CO2 eq per household t CO2 eq per 1000m2 of office Brisbane SG Brisbane DG Sydney SG Sydney DG Canberra SG Canberra DG Melbourne SG Figure 3: Greenhouse gas emissions savings from substituting coated glass in commercial building expressed in tonnes of CO2 equivalents per 1000 m 2 of floor area Brisbane SG Sydney SG Canberra SG Melbourne SG Figure 4: Greenhouse gas emissions savings from replacement of existing glazing with coated glazing in residential building expressed in kgs of CO 2 equivalents per household 11 Eco Priority Guide: Smart Glazing Selection: Ecospecifier 2015 Page 9 of 15

10 3.6 What is Mean Radiant Temperature and why is it so important? Mean Radiant Temperature (MRT): is the average temperature of the surroundings to which the body is exposed. Two types of temperature are important: air or dry bulb temperature, and radiant temperature: If the temperature of the surrounding surfaces is lower than skin temperature then the body will radiate heat. Where surroundings are hotter than skin temperature heat will radiate to the body. We are particularly sensitive to mean radiant temperature- it is more important than the dry bulb air temperature if people are lightly clothed. Human skin is a very good absorber and emitter of heat. Indeed, as can be seen from the figures below, the body is four times more sensitive to radiant gains (and losses) than any other pathway and more than twice as sensitive as all other pathways combined. The heat exchange pathways of the body and their contribution to total body heat exchange are as follows: Radiation 62% Evaporation 15% Convection 10% Respiration 10% Conduction 3% 12 Comfort can be achieved by different combinations of dry bulb and radiant heat. When glazing is externally unshaded and in the sun, it becomes a major source of radiant heat and a major source of discomfort if a person is within even 6-8 metres of the glass while it is subject to direct solar gain. Consider Table 2 below: Table 2: Equivalent Mean Radiant Temperatures 12 If a radiating glass surface at a temperature of approx 27 o C can increase an internal air temperature of approx 13 o C to the comfort equivalent of 21 o C, i.e. an equivalent heating effect of 8 o C, what happens to an occupant s comfort if the internal temperature is 23 o C (a common summer setting now)? In effect this means that a person within radiant range in front of the glazing is being subjected to the equivalent of 31 o C. As can be seen from the graph in Figure 5 below, at 50% relative humidity, this is well outside the comfort zone. Eco Priority Guide: Smart Glazing Selection: Ecospecifier 2015 Page 10 of 15

11 31 o C, 50% Relative humidity, is decidedly uncomfortable Figure 5: The Building Bioclimatic Chart showing discomfort at 31oC, 50% humidity. Source: D. Baggs, adapted from Olgay 13 Based on current experiences in the marketplace where many buildings are suffering radiant heat comfort problems, yet have been designed by some of Australia s leading environmental mechanical engineers with sophisticated thermal modelling and comfort estimation programs, it would seem that the models or processes being utilised, are not taking MRT detail into proper consideration. Hence, when considering the glazing types suitable for windows, cladding, skylights and vision panels to atria or courtyards it is important to optimise glass type with external shading and to get the design of the shading correct (see External Shading eco priority Guide for more detail on shading design). While there are a variety of shading options from double walls to conventional shading that will combat the problem, the industry is in the process of learning the hard way, there is no substitute for external shading. 3.7 What does Building Codes of Australia regulate relating to glazing? The Building Code of Australia Section J, Deemed to Satisfy provisions regulate the aggregate conductance and the aggregate solar heat gain by multiplying given conductance and solar heat gain factors by the area of the floor a each storey based also on given solar exposure factors and required shading levels. It gives tables of worst case or generic windows that can be varied by use of WERS and other sources 14. Eco Priority Guide: Smart Glazing Selection: Ecospecifier 2015 v 4 Page 11 of 15

12 3.8 What Green Star Credits are available? The Green Star tools are consistent across both the Design & As Built as the Interiors tools in awarding contributional points in the following credits: Indoor Environment Quality: Daylight Glare Control Visual Comfort - Glare Reduction. In both the Design & As Built and the Interiors tool, it is a minimum requirement of this credit that the glare, in the nominated area, from sunlight through all viewing facades is reduced through a combination of blinds, screens, fixed devices, or other means. Indoor Environment Quality: Visual Comfort Daylight. Properly designed glazing can contribute as much to good daylight levels as to minimising glareparticularly when used to bounce daylight onto ceilings. Indoor Environment Quality: Thermal Comfort. High performance glazing can, if well designed, contribute to a higher level of thermal comfort in a building. Energy: Greenhouse Gas Emissions. Where external shading is modelled in the building energy load simulation and greenhouse gas emission prediction process, significant greenhouse gas emission savings will be directly attributed to glazing type selection. 15 Materials: Sustainable Products. If the product is either a reused product, recycled content product, has a stewardship program in place, or holds an Environmental Product Declaration or a Third-Party certification, it will receive Sustainable Products credits. Materials: Life Cycle Impact Comparative Life Cycle Assessment. Credits can be obtained when a whole-of-building Fitout whole-of-life life cycle assessment (LCA) has been carried out. Furthermore, in the Performance rating tool, the Daylight, Thermal Comfort and Greenhouse Gas Emissions credits are applicable as well, along with the following credits: Indoor Environment Quality: Lighting Comfort General Illuminance. Where the lighting levels in regularly occupied primary spaces are appropriate to the tasks performed in each space, this credit is relevant. Materials: Procurement and Purchasing Refurbishing Materials. Where refurbishing and maintenance materials are purchased in accordance with the procurement framework during the performance period, this credit is relevant if they have EPDs or are third party certified by a GBCA recognised body such as Global GreenTag. Eco Priority Guide: Smart Glazing Selection: Ecospecifier 2015 v 4 Page 12 of 15

13 3.9 How does the embodied energy of glass types compare? Glazing type Embodied Energy (MJ/m 2 ) Float 15.9 Toughened 26.2 Laminated 16.3 Tinted 14.9 Table 3: Comparative Embodied Energy of Glass Figures 16 : *These figures are based on process data, are approximate only and do not include input/output data from the National Accounts. Original calculations by W. L. Lawson 16 figures either fully or partly derived from Viridian data derived from manufacturer. 4.0 Quick Guide Window Glass For: Clear Float Against: High optical clarity High visible light transmission High solar transmission (for direct gain systems) Recyclable High thermal and solar transmission For: Reflective Against: High optical clarity Reduced solar transmission Recyclable Moderate visible light transmission Potential for re-radiation of absorbed heat For: Toned & Super Toned Against: High optical clarity Moderate to low solar transmission Recyclable Moderate to low visible light transmission Potential for re-radiation of absorbed heat Eco Priority Guide: Smart Glazing Selection: Ecospecifier 2015 v 4 Page 13 of 15

14 For: Low-E Against: High optical clarity Moderate to low heat loss High daylight transmission Hardcoat pyrolitic is relatively durable and can be used as single sheet (with specific cleaning requirements) Recyclable Softcoat must be used internally in IGUs subject to damage Pyrolitic can be damaged by Windex Blue For: Double glazed - IGUs Against: High optical clarity Low to very low heat loss High daylight transmission depending on glass types used Lowest possible heat loss characteristics besides triple glazing etc Can vary glass and gas infill types for increased performance Higher embodied energy offset quickly by energy savings Potentially reusable depending on age and exposure Recyclable Higher embodied energy Less recycling efficiency because of sealed junctions at edges. For: Self Cleaning Against: High optical clarity Major energy and cost savings Needs to be exposed to sunlight for catalytic action to occur For: Patterned Against: Uses 95% recycled glass Fully recyclable Same thermal performance as single float glass Eco Priority Guide: Smart Glazing Selection: Ecospecifier 2015 v 4 Page 14 of 15

15 References: 1. Accessed 30 July 2007, 2. Accessed 30 July 2007, ser_us.pdf 3. Accessed 30 July 2007, 4. Viridian, (2015), Viridian Architectural Glass Specifiers Guide, CSR Limited, Melbourne. 5. Baggs, D, Issacs, T. and Wilrath, H, (2006) Building Thermal Performance (Residential) National Accreditation Course, ABSA and AGO, Sydney 6. Low Emissivity Coatings, accessed 30 July 2007, 7. Accessed 30 July 2007, 8. Accessed 30 July 2007, 9. Frame, I, and Gramlich, T., Pers. Comm. 6 th August 2007, Brisbane 10. Accessed 30 July 2007, Grant, T. and Sjoberg, A., (2007), A Draft Report, Analysis of the Energy Advantage of Using Low-Emissivity Hard Coated Glazing in Residential and Commercial Buildings for Pilkington Australia, RMIT, Melbourne 12. Accessed November 2006, at ology_1_interior_environments.htm 13. Olgay, V., (1965), Design with Climate, Princeton Univ. Press. In Baggs, D, Issacs, T. and Wilrath, H, (2006) Building Thermal Performance (Residential) National Accreditation Course, ABSA and AGO, Sydney 14. ABCB, (2007) Building Code of Australia, Canberra 15. Green Building Council of Australia, 2006, Green Star Office Design and Office Interiors, Technical Manuals, GBCA, Sydney 16. Lawson, W.L., (1995), Building Materials Energy and the Environment, RAIA, Canberra. Eco Priority Guide: Smart Glazing Selection: Ecospecifier 2015 v 4 Page 15 of 15