Determine whether natural ventilation is feasible based on the project type, use, and climate. Study the natural conditions of the site, such as prevailing wind direction, and orient the building to maximize airflow.
Case 2: Naturally Ventilated Spaces
Demand-controlled ventilation can greatly reduce energy use while providing large amounts of fresh air to occupants.
If you are pursuing IEQc5: Indoor Chemical and Pollutant Source Control, you must incorporate MERV 13 filters into your filtration system. These relatively tight filters may affect the fan power and fan sizes necessary to provide the required quantities of air. Involve the engineer early if pursuing IEQc5.
ASHRAE 62.1 recognizes two procedures to prove IAQ compliance: the IAQ Procedure methodology and the Ventilation Rate Procedure. The Ventilation Rate Procedure is easier to apply and is the prescribed path for this LEED prerequisite. Documentation using the IAQ Procedure requires the quantification of contaminant source emissions rates and their reduction, and has historically not been accepted for this prerequisite because it is performance-based and difficult to compare across projects.
Review the Ventilation Rate Procedure methodology in ASHRAE 62.1-2007 Section 6.2 and the associated Table 6-1.
Case 1: Mechanically Ventilated Spaces
This prerequisite is not likely to require added costs.
Check local building codes to determine requirements. The project must either meet ASHRAE 62.1-2007, or local codes if they are more stringent. Since ASHRAE 62.1-2007 is often more stringent than local codes, be sure to review and be familiar with its requirements.
Natural ventilation strategies can reduce costs. Natural ventilation in particular can reduce the need for mechanical equipment as well as operational costs. Displacement ventilation, in which air is delivered at or near floor level at a low velocity, can also reduce ducting and improve equipment efficiency. In choosing a system, analyze life cycle cost tradeoffs.