Frequently Asked Questions (FAQs)

15.   Balanced Ventilation systems - The key to energy efficiency?

When building a new house the issue regarding ventilation is one that must be addressed!  With the increasing demand for energy efficient buildings, the end result of the design and building process are often buildings that have significantly reduced air leakage. This is the desired result of energy efficient design and construction, as reduced air leakage means reduced energy loss and therefore reduced energy consumption for heating and cooling. ie fewer gaps and cracks means less energy loss from the building. However we need adequate ventilation for all of the following purposes:

• provision of outside air for breathing;
• dilution and removal of airborne pollutants, including odours;
• control of excess humidity (arising from water vapour in the indoor air); and
• provision of air for fuel burning appliances.

Ventilation systems can place undue negative or positive pressure on a building and cause extra loss of energy through increased air leakage. With new buildings; kitchen range-hoods, gas fired heaters and bathroom, ensuite, toilet exhausts may not function correctly, if at all, due to the "tightness" of the building. As well depending on climate, moisture can be driven into the wall materials and cause mould as well as structural damage.

A balanced ventilation system solves this problem by ensuring the same amount of air enters the building as is exhausted from the building. When coupled with heat or energy recovery a balanced system contributes to the best solution for achieving the most energy efficient building. The German Passivehaus standard incorporates balanced mechanical ventilation with heat recovery to achieve the most energy efficient buildings in the world.

Existing buildings can be tested for air leakage, retrofitted with a range of energy efficient products and installed with a balanced ventilation system with heat recovery to achieve very high energy efficiency. Again the German Government Energy Agency DENA has demonstrated this with refurbishments of over 375 buildings resulting in a reduction of the energy consumption to a level well below that of a comparable new building.