Interest in sustainable building has grown over recent years, particularly in the wake of global climate change. Society as a whole are now looking to ways in which they can reduce their carbon footprint and help to prevent global warming, and passive design is one of the ways we can take advantage of this.
What is passive design?
Passive design is a concept that originated in Germany, and refers to the holistic approach to constructing environmentally-friendly homes. Passive design is the key to sustainable living. Passive houses use the climate and site conditions to provide a household heating & cooling, ventilation, and lighting to reduce or eliminate the need for auxiliary heating & cooling.
This reduces energy use and negative environmental impacts such as greenhouse gas emissions. A typical heating & cooling system accounts for approximately 40% of energy use in the average Australian home. This reliance on man-made sources of power contributes to air pollution in the earth’s atmosphere, adding to global warming.
Not only is air pollution bad for the environment, but it’s also hazardous to people’s health, as the fine particles in air by-products produced by heating & cooling systems can lead to a lack of proper air quality resulting in respiratory issues. Passive homes use an environmentally-friendly heating & cooling system, achieved by clever home design.
Passive design works by constructing each room to utilize natural resources of heating and cooling such as the sun for warmth and the shade or breeze for cooling. A well-designed passive home is constructed to minimize unwanted heat gain or loss, allowing you to stay warm in the winter and cool in the summer.
Passive design steps to take with your new home
Passive design can be incorporated to new and existing homes. In order to increase the energy efficiency of your home, and reduce your carbon footprint, follow these helpful design steps:
1. Identify your climate zone
For an efficient passive design strategy, you must take advantage of your local climate. In Australia, the eight climate zones used in Your Home are defined by the Building Code of Australia (BCA). For most Australians living on the coast, climate zones can be defined as either cool temperate, mild temperate, or warm temperate. In the northern parts of Australia, e.g. North Queensland and the Northern Territory, zones are generally defined as either warm humid summer, mild winter, and hot humid summer, warm winter.
For each of these climates there are certain design steps you can implement to work with the local temperature, allowing you comfort all year round. For the more temperate, southern parts of Australia the focus will be on designing your home so that there is sufficient cooling during the warmer months and good heating for the cold months. In the more humid climates, the focus is on providing enough cooling by encouraging natural air flow and utilizing shading options.
2. Passive heating
Passive heating relies on solar power to heat your home. Passive solar heating aims to keep out the summer sun and to keep in the winter sun, ensuring your home’s thermal performance keeps your home warm when it’s cold outside, and cool when it’s hot outside. Passive solar heating is achieved by:
- North-facing building design to obtain full sun
- Insulation of walls and roof
- Masonry tile floors
- An absorber (a wall designed to absorb heat)
The biggest benefit of passive heating design, aside from saving money on utility bills, is that it makes heating your household more efficient. This consequently leads to less reliance on conventional heating systems. Having passive solar heating also eliminates noise pollution. Unlike furnaces and heating systems, passive heating relies solely on the heat from the sun, offering a quiet and comfortable home.
3. Passive cooling
All Australian climates require cooling in the summer. Tropical climates, due to the constant hot and humid weather, require year-round shading for cooling. Passive cooling can be achieved through verandas, underfloor ventilation and shady plants. Other ways to passively cool your home is by:
- Shading windows
- Using lighter coloured roofs to deflect heat
- Using insulation to minimise conducted and radiated heat gains
- Use of fixed eaves or pergolas to provide deep shade
Elevating your home allows for increased ventilation and exposure to cooling breezes, and is recommended for those living in tropical, hot climates. Sources of passive cooling are more varied and complex than passive heating. Passive cooling centres around air movement, evaporative cooling, and earth-coupled thermal mass.
4. Thermal mass
Thermal mass refers to the ability of a material to absorb and store heat energy. High density materials like concrete, bricks, and tiles requires a lot of heat energy to change their surface temperature. Thermal mass is used to absorb and store this heat energy from the daytime sun and re-radiate it at night when the outside temperature drops.
Thermal mass materials can be used in the flooring and walls of your home to provide appropriate levels of temperature control. Thermal mass acts as a thermal battery by absorbing heat during the day and hotter months and releasing it at night to help keep the house warm. For full effectiveness, thermal mass must be integrated with sound passive design techniques.
5. Sound passive design
Integrating sound passive design features such as insulation, glazing, window placement & size, and shading into your passive home will help to ensure full-effectiveness of your renewable and sustainable energy. In hotter climates, the goal would be to keep heat out of the home by placing windows out of full, direct sun. Placement of doors and windows can be utilized so that they deliver good cross-ventilation.
For cooler climates or for existing homes where window placement may not be in the position for ideal passive heating & cooling, the addition of glazing can compensate for aspects of the home that are not passively-sound.
Incorporating passive design principles at the design stage is the most cost-effective way of achieving the full benefits of a passive home, as design elements can be carefully planned and built in accordance to sun position and natural elements surrounding the house.
Sustainable living with passive home design
Passive home design is an environmentally-friendly approach to increasing the energy efficiency of your home. By incorporating passive design strategies, you are reducing and even eliminating the need for conventional energy sources. Passive homes are a cost-effective way to keep your home healthy and comfortable all year around.
Get in touch with the friendly team at Gemmill Homes, we’ll walk you through how our homes can be made to suit a sustainable lifestyle by using passive home design.