Green Living Trevor Lee, Nigel Coates and Michaele d’Onofrio
Green Living brings together design, technology and lifestyle.You can have a home that is a joy to live in - all year round. Energy efficiency is a significant contribution to sustainability. If we accept that sustainable building is ‘development that meets the needs of the present without compromising the ability of future generations to meet their own needs’ (Brundtland, 1987), closer attention needs to be given to materials selection and construction techniques as well as water and waste implications.
act winning homes 2011
Design - the first factor • Orientation • Shading • Ventilation • Landscaping • Close Neighbours
As we come to understand the interaction of environment and the use of appropriate building materials, the design of new homes, refurbishments and extensions can incorporate significant elements to enhance the performance of the house to achieve a more enjoyable and environmentally sustainable home to live in. This means we enjoy all the benefits that nature allows through clever design; and we have a home that is much more commodious to live in and a property that has a much reduced impact on the environment through the lower emission of greenhouse gases. Orientation of the property looks at the ability to maximize the warming sun into your home during winter months and allow for the reverse in summer, namely to reduce sun penetration and provide suitable shading. With good orientation the need for auxiliary heating and cooling is hugely reduced or even eliminated. Also, especially with smaller blocks, designing to keep your windows clear of your northern neighbour’s winter shadows will give a much more satisfying result. A designer experienced in both orientation factors and efficient building processes will
act winning homes 2011
greatly enhance the benefits available to you often without any increase in price. A well designed home will take advantage of the sun in winter and shields against it in summer. Shielding can be achieved through elements of natural landscaping, correct eaves application and shading elements appropriate for the regional conditions and the site. Also, with attention to tree selection and siting, the landscape can provide food as well as judicious shade to suit the seasons. A well orientated home will also take advantage of cooling summer breezes by way of cross ventilation, and may even incorporate automated systems that open up the home to take advantage of cooler night temperatures. All this great design incorporating orientation, shading and ventilation elements is enhanced further through good insulation processes, colour selection and the use of thermal mass. Thermal mass is the ability of a material to absorb heat energy. A lot of heat energy is required to change the temperature of high density materials like concrete, bricks and tiles, so they are classified as high thermal mass building materials. Lightweight materials such as timber have low thermal mass. The application of appropriate levels and locations of insulation elements in association with well designed heat capture, storage and release, creates an enjoyable, efficient, low cost environment. Also, with correct design and building application, the reverse in summer is achieved to ensure the home stays much cooler without the need for air conditioning.
Creating the Living House
Construction - the second factor • Infiltration or draughtiness • Mass • Structural framing • Window frames • Glazings
An energy efficient house relies heavily on the ability of the outer “skin” (floor, walls and roof ) to maintain comfortable living conditions inside the house. If the skin leaks air, conditions inside will quickly match those outside. You can either pump energy into the airconditioning and heating systems or sort the problem out at the source. Obvious weak points are around door and window frames and the doors and window sashes themselves, where electrical fittings penetrate walls and ceilings (especially incandescent downlights), ducting grilles and fireplace flues and of course suspended timber floors. All of these potential problems can be avoided by more careful fitting of wall wrap, insulation, seals, duct registers and floorcoverings. Same thing if the skin is able to conduct heat easily from one side to the other, conditions inside will quickly match those outside. The answer is to provide effective insulation. A combination of a reflective barrier (foil) and closely fitted bulk insulation (batts and blankets) to maintain a still air space is becoming common practice but care needs to be taken to install this correctly. Roofs require reflective foil (sarking) under tiles or anticon foil-faced blanket under metal roofs together with snugly fitted ceiling batts. Timber floors benefit from bulk and/or foil insulation although a bigger problem here is often air infiltration through the cracks. Concrete slabs should be insulated around the perimeter to take full advantage of earth-coupled thermal mass and to prevent excessive heat loss, especially when in slab heating is installed. We’re still carrying most of a home’s roof loads through the
Complete upgrades of your home Audit and rating Renovations and Extensions Design and Construct
exterior walls so the structural framing members are typically part of the outer skin. They are usually either steel, which is a poor insulator or timber which is a better insulator (but nowhere near as good as the batts installed in the wall). Care needs to be taken to provide an effective “thermal break” between steel structural members and cladding materials to avoid flanking heat loss and even condensation problems. Like the building skin itself, window frames may be made of materials which are either good insulators like timber or plastics, good conductors like steel and aluminium or composites which take advantage of the best qualities of both. Glazing needs to be appropriate to the orientation, exposure and size of the window unit. There’s a huge range of options available to maximise the thermal and acoustic performance of glazed panels which includes specialised coatings, laminated films, tinting, reflective films and insulated glazing units (IGU’s). A standard double glazed IGU can more than double the insulation value of an appropriately framed window and further improvements are possible if one or more panes are thermally improved glass. Increasing the size of the air gap between the panes, or even filing it with argon gas, also substantially improves the performance of the window. The effectiveness of the combination of frames and glazings is readily comparable through the Window Energy Rating Scheme (WERS) with separate ratings for heating and cooling situations. High heating ratings are best for the Canberra region but cooling ratings can also be important for unshaded westerly windows.
Naturally Warm Naturally Cool
CANBERRA 18 G R E E N H O U S E P L A N S
Materials - the third factor • Insulation (including framing members) • Colour • Floor coverings • Embodied energy • Toxicity and LCA with Ventilation
An effective skin with well placed windows also allows us to control the performance of the most useful tool we have for maintaining thermal comfort within a building designed for a ‘heating climate’, materials with thermal mass. They are slow to take up thermal energy and slow to give it up. This ‘reluctance’ to change temperature is known as thermal inertia or lag. We can take advantage of this characteristic with good passive solar design. Common building materials such as reinforced concrete (especially floors) and brickwork (interior walls) are placed where they can receive free solar energy during the day in winter. The stored warmth is released into the rooms through the night. In summer the same materials are protected from receiving thermal energy. They now have a cooling effect during the day after giving up any energy absorbed during the day to cooling natural cross ventilation over night.
act winning homes 2011
So we are relying on the skin of the building to act like a good esky to keep what’s inside at a constant temperature, hopefully without the need to pump energy into airconditioning and heating systems. Like an esky, the insulating materials are not particularly durable or pretty so we can choose from the entire range of exterior finishes for our building as long as the insulation is a good match. Reflective foils, cellular reflective foils, double walled reflective foils, foil faced insulating blankets, wall and ceiling batts, rigid foam panels and inserts, fibreglass, polyester, natural wool, rockwool, cellulose, EPS beads, non itch, recycled, recyclable, composite, bonded … often designated according to their heat flow resistance (called an R-value). The bigger the R-value, the better is the insulation. Insulation may even be inadvertent and detrimental. The beneficial thermal mass of an earth coupled concrete floor may be masked by choosing insulating floor coverings such as floating timber floors act winning homes 2011
PASSIVE SOLAR HOME
tel: (02) 6260-6173
www.exemplary.com.au or carpeting; (However, if that floor is suspended and exposed to the cold air from beneath., that same insulating finish can improve the comfort of your home). If you aim to produce an energy efficient house and save a bundle on your energy bills then passive solar design and a well constructed skin protecting strategically placed thermal mass will get you there. If your aim is to build a house that is sustainable then you’ll need to consider whether the materials have come from a sustainable and renewable resource. Is it recycled or recyclable and what do I do with the waste? Is the product local and can locals install it? And how much energy is needed to produce and transport the material to site before it’s installed? Most building materials require a certain amount of energy to produce and transport to site before actually being incorporated into the building. This is called the embodied energy of the product and is measured in megajoules/kilogram (MJ/kg as in Lawson, 1996). A mud brick might be hand made on site from materials dug up on site and laid by local labour. The embodied energy in a mud brick wall that uses no cement would be almost nil, but to build a clay brick wall using cement mortar, the clay would be quarried, transported, processed, kiln fired, transported, probably up to three times before it arrives on site, moved around on site, and laid in cement mortar using sand which has no doubt travelled and cement which has been produced by a process even more energy intensive than brickmaking. However, the bricks are durable, reusable and recyclable so the life of the material relative to its embodied energy becomes a mitigating factor.
Dark colours soak up solar heat and grow hot. Light colours reflect most of it and stay cool. The choice of a light coloured or reflective roof covering will significantly reduce heat gain in summer when compared with darker colours in the same materials. By choosing a roof material that’s able to cool quickly when the sun goes down, the roof won’t continue to radiate heat into the ceiling cavity all night long in summer. However, those same effects will be beneficial in the winter so a darker roof will increase a house’s EER in Canberra’s climate.
Systems - the fourth factor • • • • • • •
The annual savings shown here are only part of the story. For high rating homes with insulated ducts, the heater and cooler can be smaller (and cheaper) and still keep you comfortable year round at lower up front cost. And, of course, once the “price on carbon” is introduced, the savings will be even higher again.
Heaters and coolers Ducts and pipes Hot water Water outlets Rainwater Grey water Solar electrics
The meaning of Sustainability is often stretched to fit the Heaters and to a lesser extent coolers are almost as circumstances. If we embrace the definition given in the important as the house itself in determining the energy use Brundtland Report, or the concepts of ‘Cradle to Cradle’ and GHG emitted by a home. Most are now energy rated Sustainability put to us by William McDonagh (McDonagh with a star scale so that we can calculate the combined and Braungart, 2008), ideal materials should be renewable impact of the home and appliance together. You can look and infinitely recyclable in the environment without ever up your combination of star ratings in the table below to needing to be downgraded to a lesser product. Life Cycle see how much you might save by improving your house, Assessment (LCA) is used as a compelling argument for your heater/cooler appliance or both. materials which may have a long service life when compared with the energy used to produce them, or have Stars 1 2 3 4 5 6 7 8 9 the potential for being recycled at the 1 $2,564 $1,425 $1,008 $739 $560 $426 $311 $199 $92 end of that life despite the fact that 2 $1,849 $1,277 $904 $663 $502 $382 $279 $178 $82 they may not come from a renewable 3 $1,642 $1,134 $802 $588 $445 $339 $247 $158 $73 resource. 4 $1,439 $994 $703 $515 $390 $297 $217 $139 $64 5 $1,240 $856 $606 $444 $336 $256 $187 $120 $55 Some materials are even toxic or 6 $1,044 $721 $510 $374 $283 $216 $157 $101 $47 potentially toxic to the environment 2 Annual Energy Costs for a 200 m single storey home but are marketed on the basis that they may help to reduce energy consumption during a long but single life. Some materials ‘off gas’, making These tabulated values do not include for duct or pipe the air quality within buildings unhealthy to the extent that losses which can be huge in old systems. New ducts are we now have the phenomenon of ‘sick building syndrome’. required to have insulation of R1.5 (not even as good as Extra ventilation is usually used early on to control the walls, let alone the ceilings even though the hottest air these effects until the ‘off gassing’ declines to negligible flows inside them). Before the regulations were introduced amounts in time. There’s usually a healthier alternative in 2006, R0.6 was most common and the worst systems to materials which release potentially toxic chemicals had foil only spiral wound ducts with a very poor equivalent and a growing awareness amongst manufacturers that rating of R0.3. For a 200 m² single storey home, there is consumers are aware of this. typically 61.3 m of duct length with a surface area of 56.6 m² including junction boots exposed to the cold (and heat) of the roof space. The table below allows you to estimate how much you will save by choosing better ducts or replacing old substandard ones. Ironically, the lower is the rating of your home and heater/cooler the greater are your savings from upgrading your ducts
We should all be encouraged to think carefully about our choices of building materials. Will our choices enhance our own well being without compromising the ability of future generations to meet their own needs?
Figures based on current retailer prices (2.0614 cents/MJ for Gas and 15.598 cents/kWh for Electricity, release of new rates imminent.
Hot water is a big cost for most homes – bigger than heating and cooling in mild coastal climates. Off peak electric systems are being phased out due to their large greenhouse gas emissions so that consumers must now choose between heat pump electric, solar and gas with the best systems being gas-boosted solar or instantaneous gas (5- or 6-star rating). Water outlets matter too. Low-flow shower heads can save half of the hot water in a family and another 10% can be saved through fitting aeraters to sink and hand-basin taps. and choosing high (WELS)-rating toilet suites. And big water using appliances like dishwashers and laundry equipment have water ratings as well as energy efficiency ratings to help you make sound selections in the beginning as well as at replacement time. Consumers can now receive support from the ACT Government for installing a rainwater collection system provided that it is connected with a pressure pump to toilet cisterns for flushing and grey-water treatment systems are commercially available which will render the non-toilet waste-water suitable for use in the garden. Both of these reduce the demand for mains water and reduce your bills from Actew. The ACT was a national leader in providing an attractive feed-in-tariff for consumers to sell their solar-generated electricity to the grid, making those systems costattractive. Typically a 2 kW system on an unshaded north-facing roof at 25° pitch will cost $8-9,000 nett of government support and earn the household $2,100 per year in sales to ActewAGL. With the end of the promotional scheme in May 2011, these annual earnings are reduced to around $700 for subsequent systems.
Occupants - the fifth factor • • • • •
Ventilation and infiltration Window furnishings Thermostat settings and internal zoning Internal water use Irrigation
Efficient homes and appliances (those with high star ratings) provide the potential for low cost and comfortable, sustainable homes; but the way the family lives in the home and uses the appliances is just as important. Careless families can use over twice as much energy and water as attentive ones in identical situations – homes and appliances. Especially with single glazing, the choice of window furnishings is a key barrier to costly heat flow. Venetians and vertical venetians offer scant resistance to heat flow while insulating drapes or twin-wall blinds like Luxaflex Duettes, can insulate almost as well as double glazing. Light coloured backs assist in reflecting the sun out in an unshaded window in summer as well. Also, controlling the windows and curtains to let in the sun in winter and not in summer and let the breezes in on summer evenings helps get the best out of your home. Thermostat settings and internal zoning can also have a big impact on energy use. Letting unused rooms or zones of rooms go unheated (or uncooled) can achieve a saving commensurate with the floor area isolated. Similarly, a 1° change in thermostat setting can save up to 10% of the heating and cooling over a year as it shuts down the appliance in the more mild weather and does not work as hard when conditions outside are harsh. Internal water use is also up to the householders. Only doing full loads of dishes and laundry saves on water and hot water (where cold washes are not selected) as do shorter showers and less frequent baths. So too with gardening: drip irrigation and selection of native or other climate-fitting landscapes can save two thirds of the water traditionally used outside the house.
2 Assumes 180 m2²of conditioned area with a ratings standard 4-person household and with 85% of the energy demand being gas heating and the remaining 15% being refrigerative airconditioning at current Canberra fuel process 2.0614 c/ MJ for gas and 15.598 c/kWh for 96electricity. Release of rates for 2011-12
3 High Energy = 2-star house with 2-star appliances Low Energy = 6-star house with 6-star appliances
R1.5 is the minimum permitted in Canberra under the Building Code of Australia 2011
High Energy House Low Energy House
Ducts Foil Cooling $326 Heating $1,548
R0.6 $130 $405
R1.0 $84 $261
R1.5 $45 $138
R3.0 $28 $84
Cooling $128 Heater $849
Indicative Annual Energy Costs from Ducts in the Ceiling of a 200 m2² one-storey home
act winning homes 2011
act winning homes 2011
Alterations & Additions
• Measuring the exemplary
• Measuring the exemplary
When you refurbish or extend your home it is the best opportunity in years to improve your Green Living at a low and affordable cost. If you are making extensive additions, more than 50% of the existing place, you will be required to bring the energy efficiency of the whole house up to current standards – an EER of 6 stars. More modest changes present an opportunity to improve the existing house at your option – only the new parts need to be built to modern standards provided they do not cause detriment to what already exists (perhaps by shading a north-facing window). But while the building trades are on site is a golden time for going the extra distance: top-up insulation in the roof, blow-in water repellent insulation inside the walls (brick veneer gets the equivalent of R3.0 from this technology), under-floor insulation, new colour schemes, ventilation controls, shades, new ducts in the roof, a solar water heater … creative enhancement of your comfort and shrinking of your environmental foot print is available in almost as many ways as for a new home.
The Building Sustainability Index (BASIX) is the environmental quality assessment process of the NSW Department of Planning applying to new housing and substantial extensions. It covers heating, cooling, hot water, appliances, lighting, water, waste water and landscaping and targets new developments as being 40% more efficient than the long term average for that climatic region. These target values are set on a per person basis and the number of bedrooms is used as the planning indicator of the number of people who will live in the proposed home. Compliance is demonstrated by inputting details of the new dwelling into the BASIX website (basix. nsw.gov.au). Householders can do this using the DIY option but the site does not protect you from making expensive selections and the site generates a list of key things that must be achieved in the finished dwelling which certifiers and councils will require before confirming completion to allow .occupancy.
And if you want to do better than merely meet current minimum standards of design and construction, there are many ways to do that too and to demonstrate to buyers that you have done so to reap the increase in resale value as well. The EER scale runs right up to 10 stars (a house that needs no heating nor cooling year round).
- what the 5 factors deliver • Energy savings • Greenhouse reductions • Water savings • Resale value
In both cases, design is the key that allows your builder to bring your home into the 21st century at a manageable cost that pays for itself in a myriad of ways.
The energy savings potential of the home and its heater and cooler systems with a little attention from the householders has already been described on page 96 but those savings also have the environmental benefit of reducing the greenhouse gases emitted by your home. For every $1 worth of electricity you buy (unless it’s GreenPower) you will be emitting over 7 kg of those gases. Similarly for natural gas, for every $1 you spend the emissions are just over 3 kg.
Special advise for country NSW
As you enter data the site gives you feedback on the percentage of the long term average that your proposal will demand from the state’s electricity, gas, water and wastewater systems and not allow completion until the 40% better standard is attained. The site will also allow further improvements to be entered, such as a high performance house (say 7.5 stars) and display even greater reductions which can then be used as a marketing testimonial of the design. While the BASIX scheme recognises the nationwide house simulation software, it ignores the star ratings and sets instead separate heating and cooling energy “caps” so that the home must perform acceptably in summer and winter. Star ratings allow designs which excel in one season but underperform in the other. An example of this difference would be that the star scale would allow a large unshaded north-west window (good in winter, poor in summer) where BASIX would not – but BASIX approximates to a 5-star standard while most other jurisdictions have advanced to 6-stars.
Water savings also reap benefits in the form of lower bills. Every kilolitre (kL) that you save will reduce your bill by $4.66 and improve the water security of the ACT.
Green Living has its attractions and as a result buyers are willing to pay extra for a home that fosters conservation and creative use of our resources. This is best seen in the EERs for homes advertised for sale or rent. Advertising websites let you sort by the number of stars to find a good one (or an old low rating one to do up and enhance) and the Bureau of Stats (ABS, 2008) has found a strong connection between EER and sale price so your investment will come back to you in increased resale value.
act winning homes 2011
act winning homes 2011
• History of the ACT pre and post BCA 3 stars • Table of scales for NatHERS plus Heater/Cooler Stars • NatHERS and resale value • Other appliances In Australia, energy efficiency requirements for new housing began with mandatory minimum insulation levels required in the ACT and Victoria (and a few individual municipalities elsewhere) in the early 1990s. A more comprehensive scheme including simulation software followed a few years later in Victoria and the version of that program for the Ballarat uplands was renamed ACTHERS and adopted in the ACT under the Territory Plan with a 3-star phase in before requiring 4 stars in1996. In 2003, the housing star scale was adopted by the Building Code of Australia for houses, with the ACT confirming a 5-star standard along with most of the country at that time. Similar standards for flats and apartments followed a few years later. Unfortunately, the 5-star standard was set in the 1980s by an industry initiative led by Professor John Ballinger (UNSW) using the prestige of the term “5 Star” to denote what the innovative end of the housing industry was willing to adopt at that time. As a result, customers imagine now that the 5-star standard denotes high performance when it actually denotes standards too low to be permitted to be built. The scale is, however, future-proofed now by defining 10=star as zero energy for heating and cooling (but allowing some energy for dehumidification which normally happens integrally with cooling in air conditioning systems). Major electrical appliances have been star-rated for a similar period (energyratings.gov.au) and gas appliances more recently. In those cases, as is true for commercial buildings energy ratings too, 6-stars denotes excellence as it does in all other fields (like hotels and movie reviews). This presents a clash with customer expectations because home buyers think that 5- and 6-star homes are excellent rather than merely being compliant with modern minimum standards. Even so, the star rating (EER) has a significant impact on resale value and home-marketing websites allow sorting by EER to help buyers find homes reaching modern standards (or poor homes which will respond well to cost effective improvements during a refurbishment). The correlation between price and EER has been tracked in the ACT over 12 years and makes interesting reading (ABS, 2009).
Support and further information
• MBA members
• Energy Partners
Temperatures through a Cold Week in Bega
EER of Canberra Homes Sold over Time
Tempe erature (°C)
NatHERS Stars & Appliance Stars
Optimise your dream home
The ACT Government funds a home energy audit and advice service for householders, house buyers, renters and those set to have a new design built anew. For advice, go to www.heat.net.au or phone 6260 6165 where you can also seek an audit of a pre-1996 home where the process begins with you providing them with confidential copies of your gas and electricity bills for at least the last 12 months. They also disseminate the “HEAT Fact Sheets” on a wide range of householder points of interest. For new homes, extensions and refurbishments, guidance can be found through Master Builders Association of the ACT members and, for a fee, from the Architects Institute Archicentre service.
www.exemplary.com.au I 6260 6173
Energy Efficiency Rating (EER Stars)
Trevor Lee is the Director of Buildings with Energy Partners
• • • •
Kitchen and Living
Water Energy Waste Health and Toxicity Life Cycle Evaluation
Energy Efficiency Ratings (EERs) Home Energy Audits Cost effective code compliance for new homes 10-Star Challenge for keen households
Energy Partners: tel: (02) 6260-6173
www.mba.org.au I (02) 6280 9119 www.archicentre.com.au I 1300 134 513 Detailed evaluation of designs before they are built is available through Energy Partners in terms of energy and comfort and cost.
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highest comfort lowest cost lowest running cost
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Design advice Simulation and ratings BASIX for NSW
References ABS, Australian Bureau of Statistics, 2008, “Energy Efficiency Rating and House Price in the ACT”, published by the Department of the Environment, Water, Heritage and the Arts Bruntland, Gro Harlem, 1987, “Our Common Future”, World Commission on Environment and Development
About the Author Trevor Lee is the Director of Buildings with Energy Partners (see page 101) while Nigel Coates and Michaele d’Onofrio are designer-builders with SunConscious Design (see page 95).
CIE, p&s, Energy Partners, 2010, Report for MBA, “Energy-efficiency: building code star-ratings What’s optimal, what’s not” Grey, Alan (ed.), 2002, “Green House Plans”, Earth Garden Books, Trentham, Victoria Lawson, Bill, 1996, “Building Materials, Energy and the Environment”, Royal Australian Institute of Architects, Canberra Wrigley, Derek, 2003, “Making your Home Sustainable”, Scribe, Melbourne NABERS Domestic www.nabers.com.au/home (National Australian Built Environment Rating System) NatHERS www.nathers.gov.au
act winning homes 2011
act winning homes 2011