Intermittent Mechanical Outdoor air Ventilation

[Guest guest]

IEQuality colleagues.

I am sorry to report that my proposed change to limit the maximum cycle times of

residential mechanical outdoor air systems was rejected in Chicago this weekend

by the 62.2 committee

I gave it my best shot but in the end I could not persuade the committee. The

committee consists primarily of mechanical engineers as this is of course first

and foremost a ventilation standard.

For those of you interested in seeing my arguments I have attached the following

three files.

Offermann Intermittent Ventilation - Chicago

Offermann 62.2 Proposed Change Presentation

Offermann 62.2 Addendum i - Proposed Change

Basically my argument is that for an intermittently operated mechanical outdoor

air system to provide equivalent IAQ to that of continuously operated system,

the cycle times need to be kept short (e.g. a maximum of 2-4 hours, btw the IRC

and IMC have a 4 hour limit). ASHRAE currently allows intermittent systems to be

operated with a maximum of 24 hours. During the long off periods of systems with

long cycle times air contaminants with indoor sources such as formaldehyde can

accumulate to high indoor concentrations causing irritation.

Two reasons that the committee members cite as for allowing intermittent

ventilation systems with long cycle times aare energy and high outdoor air

polution.

As I see it when there are concerns for energy costs because of cold or hot

outdoor climatic conditions or high time of day utility costs, then the response

should NOT be to shut off or reduce the outdoor air ventilation, but rather

energy conservation measures,

such as heat and energy recovery ventilators, should be pursued. Similarly, when

there are concerns for

high outdoor air contaminant concentrations, then air cleaning measures should

be pursued.

Buildings are for people and thus health must trump energy.

I would appreciate the groups feedcback on this issue.

3 of 3 File(s)

Offermann 62.2 Proposed Change Presentation.pdf

Offermann 62.2 Addendum i - Proposed Change.pdf

Offermann Intermittent Ventilation - Chicago.pdf