HVAC

A number of months ago we wrote about parameters to consider during the design of new facilities. We discussed:

• ventilation requirements and local exhaust ventilation
• duct systems including proper duct material, return air plenums, and terminal diffusers
• mechanical equipment such as air handlers, and heating and air conditioning control systems
• filtering media and air cleaning devices
• outside air intakes¹

In this issue we shift our focus to the construction phase and the related issues on which we should aim our attention. Construction activities invariably contaminate the building during the process. Depending on the materials affected and the type of contamination, any residuals could potentially affect building indoor air quality over the structure’s lifetime. If we keep in mind a few simple rules, it will pay big dividends in terms of worker health and productivity as well as facility maintenance costs down the line. Recent research suggests that improving indoor air quality can increase worker productivity between one and eight percent and averages about three percent. And, if we stop to consider that the average cost for employee salaries in a typical Class A building is around $150 per square foot, better indoor environmental quality can save an employer around $4.50 per square foot just from improved worker productivity. ²

By its nature, construction is a messy business. It does not matter whether we are constructing a new facility or renovating an old space, the issues are the same for the most part. However, by developing and following a good construction management plan, we can control the mess and greatly reduce the impacts on indoor environmental quality during and after the construction process. Two good resources for putting together your construction management plan are the Environmental Protection Agency’s “Indoor Air Quality Tools for Schools”³ and the Sheet Metal and Air Conditioning Contractors National Association’s “IAQ Guidelines for Occupied Buildings under Construction.”⁴ These publications discuss five or six controls to implement during your construction project. We have added one or two of our own to round out a comprehensive construction management plan. So, let’s get started.

1. Material Protection
As with life, all construction projects have to deal with the weather. This is unavoidable and can have a major impact on indoor air quality. Coordinate with your building contractor and see if his material delivery schedule makes sense. All stored materials, and especially porous material like drywall, should be protected from moisture and microbial growth. This is much easier once the building shell is dried in. Any water-damaged materials must be discarded and not used in the construction.

2. Source Control
Controlling sources involves preventing or eliminating pollutants from entering the building. For example, do not allow vehicles, machinery, or equipment to operate or idle near entries, loading docks, or air intakes. These practices could let exhaust fumes, loaded with carbon monoxide to flow into the building. Also, ensure trash and dumpsters are positioned and stored well away from these areas. One other aspect of source control is to locate or move pollution-causing activities (painting, concrete, block or brick cutting, etc.) away from building openings. Source control is also tied to housekeeping and worker education (discussed below).