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  • Ray Darrough

Passive Homes, What, When, How

With trends towards Net Zero carbon emissions becoming prevalent around the world, housing has become a focal point due to its sizable carbon footprint. Conventional Australian homes are built to rely on heating and cooling sources to provide a comfortable living environment. However, passive homes take measures during construction to provide a stable temperature that requires minimal input from other sources. By focusing on design elements to create the most energy efficient shell for the home, you end up with a stable temperature environment with very little energy consumption year on year regardless of the season.


Passive homes came about as an answer to soaring oil prices, and extend back almost five decades to 1976, when the Lo-Cal House was designed by the University of Illinois Small Homes Council. The Lo-Cal House implemented the concept of a fully enclosed envelope for the housing structure with reduced thermal bridges.


There are 5 main elements to consider when designing a Passive home:


Glazing & Orientation

Traditionally glazing (windows and doors) is an easy entry point for heat into the home. By utilising double or triple glazing with thermally broken frames, coupled with shading and changes in orientation, heat losses can be minimised and gains from solar radiation are made the most of where appropriate


Insulation

By ensuring a continuous layer of insulation from foundation to the roof you create an unbroken envelope allowing for highly efficient temperature control throughout the dwelling, regardless of seasonal differences


Airtightness

Airtight dwellings allow for use of the highest efficiency heat recovery ventilation systems whilst preventing draughts and mould.


Thermal Bridges

Thermal bridges are an element or part of a building which allows heat to travel through it more quickly than through other parts, and is therefore responsible for unwanted heat loss or gain, into or out of the home. This can occur when there are gaps between structural materials and insulation, or when materials of different insulation qualities touch each other. Thermal bridges should be avoided when designing a Passive home. Thermal bridges also bring with them a risk of moisture tracking into the home leading to mould growth.


Ventilation

Ventilation is the centrepiece of a Passive Home. Ventilation should always occur under controlled conditions, by opening windows or with ceiling or exhaust fans, NOT through gaps and air-leakage Through the years huge leaps in efficiency have been made to enable us to now deliver effective ventilation systems. Acting as your home's lungs, a Heating Recovery Ventilation system can transfer energy from the internal air to the fresh air being supplied into the premise. This enables the delivery of temperature stable, clean air year-round.



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