The air within businesses can become stale from moisture, odors, and pollutants that penetrate the building or are generated internally by human activity and out gassing from building materials and furnishings. A steady supply of fresh outdoor air can increase indoor air quality and improve occupant comfort. Commercial buildings have had consistent building codes requiring a specific amount of outdoor air to be ventilated in to the building. As envelope construction practice has improved, the commercial building envelopes have become tighter, and the need to control air quality has risen.
Any mechanical ventilation system will not reach its performance potential if components are poorly manufactured or installed improperly. Several factors contribute to poor performance of ventilation systems including long duct lengths and compression in flexible ducts, each resulting in a loss of ventilation rate and a significant increase in power and energy consumption by HVAC systems.
Advanced Code Options
There are many new and innovative mechanical ventilation products available, that can save energy, decrease utility bills, enhance thermal comfort, and improve indoor air quality. Examples include, more stringent requirements for ventilation fans, pollution or moisture-based source-point ventilation, and whole-house ventilation systems; Requirement for automatic controls or systems capable of being set remotely for continuous operation. The following sections provide examples of code improvement language or methodologies along with technical examples of how to meet or exceed code.
Commercial Policy Recommendations
Demand controlled ventilation is required for spaces larger than 500 sq. ft. and with an average of 25 people per 1,000 sq. ft. of floor area. System must be served by one of the following:
- Air Side Economizer.
- Automatic modulating control of the outdoor air damper, or
- A designed airflow greater than 3,000 cfm.
Exclusions can be made in the case that: Energy recovery compliant systems are installed, multiple zone systems without direct digital control of individual zones communicating with a central control system, system with a design outdoor airflow less than 1,200 cfm, or building spaces where primary ventilation needs are for process loads.