## Draft Proposal CA-3

This concept has been developed by the DOE Building Energy Codes Program (BECP) as a possible code

change proposal to the Commercial provisions of the 2012 International Energy Conservation Code

(IECC). Interested parties are asked to submit any and all comments on DOE's initial concepts and draft

code change proposals. For instructions on submitting comments, visit:

www.energycodes.gov/development/ commercial/codes/iecc/concepts/



## Enhance Requirements for Demand Controlled Ventilation (CA-3)

Objective: Reduce thresholds associated with space size and design occupant density at which demand

controlled ventilation (DCV) is required.

Suggested Code Change Proposal

Revise Section C403.2.5.1 as follows:

C403.2.5.1 Demand controlled ventilation. Demand control ventilation (D CV) shall be provided for

spaces larger than 500 200 square feet (50 20 m 2 ) and with an average occupant load of at least 25 people

per 1000 square feet (93 m 2 ) of floor area (as established in Table 403.3 of the International Mechanical

Code ) and served by systems with one or more of the following:

1. An air-side economizer;

2. Automatic modulating control of the outdoor air damper; or

3. A design outdoor airflow greater than 3,000 cfm (1400 L/s).

Exception: Demand control ventilation is not requ ired for systems and spaces as follows:

1. Systems with energy recovery complying with Section C403.2.6.

2. Multiple

- zone systems without direct digital control of individual zones communicating with a

central control panel.

3. System with a design outdoor airflow less than 1,200 500 cfm (600 250 L/s).

4. 3. Spaces where the supply airflow rate minus any makeup or outgoing transfer air requirement

is less than 1,200 500 cfm (600 250 L/s).

5. 4. Ventilation provided for process loads only.Reason: DCV reduces the amount of energy needed to ventilate and condition spaces with high

‐ density

occupancy because it allows the mechanical system to modulate ventilation based on occupant load,

rather than always providing ventilation based on full design occupancy. In the time since the provisions

for DCV were first included in the IECC, the cost for DCV has been reduced. DCV is now cost effective in

smaller spaces than are covered in the current code. The exception for multiple zone systems without

DDC is removed for two reasons: (1) almost all multiple zone systems installed today have DDC control,

and (2) it is possible to provide DCV controls at the zone level without DDC.

Cost Impact: There would be a cost increase associated with this code change for spaces from 251 to

500 ft 2 in floor area that are not subject to the exceptions because those spaces currently do not require

DCV and, pursuant to this code change, would now need DCV. A detailed cost analysis conducted in

support of similar provisions in California Title 24 (the California Energy Code) indicated that DCV was

cost effective down to spaces 150 ft 2 in floor area. This analysis was for relatively mild climates. In

colder or warmer climates, more energy is used for heating or cooling ventilation air, so if the

technology was cost effective in California, it will have greater savings and better cost effectiveness in

colder or warmer climates. The incorporation of occupancy sensors into DCV controls and requirements

for lighting occupancy sensors in most high

‐ density spaces has also resulted in reduced incremental

cost. As a result, DCV is cost effective in smaller spaces.