Passive design for homes of the future
Sustainable living is being embraced by global citizens more than ever before. And one way to be involved is to reduce the impact of housing using passive house design. Passively designed homes take advantage of the natural climate to maintain a comfortable interior climatei. The result is buildings that require less active heating or cooling, helping the environment and potentially slashing energy bills!.
A building with passive design is a well-insulated, virtually air-tight building that relies largely on passive solar heating and cooling to minimise energy use. Combined with factors including the building's orientation, glazing and thermal mass they form a holistic approach to building design that can result in improved energy performance.
Germany even codified Passive Design back in 1988 with a voluntary standard called The Passive House. Buildings built in accordance to the Passive House (Passivhaus) standard are said to be the most energy efficient buildings worldwideii. The standard is said to reduce energy consumption of buildings by 90%iii.
How passive design stores heat and keeps cool
Solar radiation is gained through north-facing windows exposed to full sun - window frames and glazing type affects the efficiency of this processiv.
Metal frames with high conductivity, such as aluminium and steel, are said to radiate solar heat while wooden frames do the oppositev. Different glazing products offer a wide range of Solar Heat Gain Coefficient values, enabling you to choose how much solar heat comes into your homevi.
Trapped heat is absorbed, stored and re-radiated by materials with high thermal mass such as masonry, concrete, bricks and tiles within the buildingvii. Thermal mass acts like a thermal battery, storing heat during the day only to release it at nightvii. Heat absorption can be maximised if thermal mass is placed inside the insulated building envelopevii - a term used to describe the roof, walls, windows, floors and internal walls of a homei.
Shading and well insulated walls, ceilings, exposed floors and thermal mass can minimise or increase heat lossviii. Insulation will help keep heat out or in (or both!)ix. There are two general insulation types, bulk and reflective insulationx. The former mainly resists the transfer of conducted and convected heat by trapping air within its structure, whereas the latter resists radiant heat by reflecting away from the buildingx.
Appropriate air movement to reduce or increase heat lossxi. Minimising air infiltration can increase heat gain, doing the opposite can reduce heat gain to cool the building. Air infiltration can be minimised with airlocks, air sealing the envelope, airtight construction detailing and simply by keeping windows and doors shutxii. Effective passive cooling can be achieved by maximising the flow of cooling breeze through the building, encouraging convective air movement to increase rates of evaporation and earth coupling of thermal mass (e.g. floor slabs)xi.
Passive homes: newly built or retrofitted
More than 15,000 buildings in Europe have been designed, built or remodelled to the Passive House standard over the last 10 yearsxiii. As green, sustainable living is recognised by more and more people as their preferred way of life, a passively designed home could very well be your gateway to achieving a greater energy-saving, cost-effective and comfortable lifestyle.
Although passive designs are most often applied to newly constructed buildings, passive design can also be applied to refurbish existing buildings. To date, retrofitting passive house design features to older buildings has been successful in countries such as Austria, Germany and Switzerlandiii. Retrofitting work could involve installing shades, movable shutters, glazed windows, better ventilation systems, insulation, northern windows and more to help enhance the building's energy efficiencyiii.
Passive house design principles offer an opportunity to reduce your impact on the earth as well as potentially save money on power consumption for heating and cooling. When it comes to protecting the investment in your property, home insurance can save you from financial woe in the event of damage caused to your home by one or more of the insured events, including fire or smoke, storm or theft. Visit the Allianz Web site today for a home insurance quote in just 2 minutes.
i Commonwealth of Australia, Passive design', Your home, http://www.yourhome.gov.au/technical/fs41.html
ii Air2Energy, 'What is the European Passive House (Passivhaus) Standard?, http://www.air2energy.com.au/faqs17.html
iii Ploss, M. 2008, 'Passive house retrofit: taking it easy', Renewable energy world, http://www.renewableenergyworld.com/rea/news/article/2008/04/passive-house-retrofit-taking-it-easy-52023
iv Ploss, M. 2008, 'Passive house retrofit: taking it easy', Commonwealth of Australia, ‘Passive Solar Heating’, Your home, http://www.yourhome.gov.au/technical/fs45.html
v Commonwealth of Australia, 'Glazing', Your home, http://www.yourhome.gov.au/technical/fs410.html
vii Commonwealth of Australia, 'Thermal Mass', http://www.yourhome.gov.au/technical/fs49.html
viii Commonwealth of Australia, 'Insulation', Your home, http://www.yourhome.gov.au/technical/fs47.html
ix Commonwealth of Australia, 'Passive design', Your home, http://www.yourhome.gov.au/technical/fs47.html
x Government of South Australia, 'Insulating your home', http://www.sa.gov.au/subject/Water,+energy+and+environment/Energy/Energy+efficiency/Home+energy+efficiency/Insulating+your+home
xi Commonwealth of Australia, 'Passive cooling', Your home, http://www.yourhome.gov.au/technical/fs46.html
xii Commonwealth of Australia, 'Passive Solar Heating', Your home, http://www.yourhome.gov.au/technical/fs45.html
xiii Passive House Institute US, 2011, 'What is a Passive House?', http://www.passivehouse.us/passiveHouse/PassiveHouseInfo.html