Frequently Asked Questions (FAQs)

The answer is yes they can be, provided the design of the house includes adequate ventilation with filtration. The main method currently used to significantly reduce energy loss from a building is to ensure that the building envelope (ie the building shell) is as air tight as possible. As a result, natural ventilation into the building is reduced and the issue of indoor air quality becomes a significant one.

In February 2005 the California Air Resources Board produced a draft Report on Indoor Air Pollution in California * which recommended to "Amend the building codes to address indoor air quality, with a focus on assuring adequate ventilation under all circumstances."

The report also states that: " California adults spend an average of 87 percent of their time indoors, and children under 12 years of age spend about 86 percent of their time indoors. .... the trapping effect of buildings, and people's proximity to indoor sources of emissions, there is a much higher likelihood that people will be exposed to indoor pollutants than outdoor pollutants. Investigators have calculated that pollutants emitted indoors have a 1000-fold greater chance of being inhaled than do those emitted outdoors"

In April 2006 the United Kingdom amended their building regulations to ensure that adequate ventilation is achieved in all new buildings. The UK building codes now state that:

"Ventilation is required for one or more 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." **

The four approved methods of achieving such ventilation are as follows:

• Background ventilators and intermittent extract fans;
• Passive stack ventilation;
• Continuous mechanical extract; and
• Continuous mechanical supply and extract with heat recovery.

Heat Recovery Systems can provide fresh filtered air to buildings as well as recovering up to 80% of the heat from the exhaust air, thus maintaining energy efficiency as well as providing acceptable levels of indoor air quality.

• Read the draft Report on Indoor Air Pollution in California *    pub. February 2005.
  
  
• Download document Part F "Ventilation" - United Kingdom** pub. 15 March 2006.