Whole-House Ventilation System – the breeze that pleases

Steps For Designing A Whole-House Ventilation System

1.Air seal the house as much as reasonably possible, especially the foundation, garage or other spaces from which polluted air could be drawn.

2. Choose building materials, paints, furnishings, etc., to minimize emissions of VOCs and other pollutants.

3.Select a general ventilation design strategy appropriate for the climate. Consider the type of heating and cooling system to be installed, operating costs of the ventilation system, impact of the ventilation system on heating and cooling operating costs, installation costs, and the desire or need for filtered air(an important consideration for people with asthma, allergies, and other environmental sensitivities). Ensure that depressurization will not lead to moisture damage in wall cavities in humid climates or introduction of pollutants from outside the house, and that pressurization will not lead to moisture problems in cold climates.

4.Determine the Whole-House Ventilation System requirements by consulting ASHRAE and local codes. A continuous ventilation rate of 50 to 100 cfm is typical.

5.Design the whole-house ventilation system and select appropriate equipment and controls to meet the determined ventilation requirement. In developing the design, keep operating costs (especially fan costs) as low as possible. Keep in mind the contribution of natural ventilation to a house’s ventilation requirement. Avoid providing excess ventilation because it can increase heating and cooling costs without significantly improving air quality.

6.Incorporate spot ventilation (i.e., exhausts in kitchens, bathrooms, and other rooms where pollutants are produced) and/or separate spot ventilation systems in the design, following ASHRAE recommendations and local building codes to control moisture and pollution generation at their source.

7.Include both sensible and latent loads induced by the whole-home ventilation system in calculations for sizing heating and cooling equipment.

8.After installation, balance and test the system. Make sure whole-home ventilation system ducts are air tight, design air flows are achieved, control systems work as intended, and controls are clearly and permanently labeled with operating instructions. Provide a homeowner’s manual that covers operation and maintenance details, especially for heat-recovery ventilation systems and systems with filters.

9.Consider hiring a specialist to select and design the whole-house ventilation system. Ideally, one engineer should design both the ventilation system and the heating and cooling system, especially if the ventilation system is to be integrated with the heating and cooling system.