ASHRAE 62.1 for multi-unit residential

[WinniPEng]

Here in Canada, the new Building Code prohibits providing ventilation air to apartments via pressurizing the corridor, and transferring into the suites. We now find it preferable to introduce ventilation air directly to the suite's fan coil, to meet the outdoor air requirements. The suites in this case each have a 100 cfm range hood, and two 50 cfm bathroom fans, which meet the minimum required in Table E-2 of the ASHRAE 62 standard. Since these fans are intermittent, and the outdoor air intake is open continuously, how can I determine how much cfm of outside air is needed to make-up for this exhausted air? The requirement to meet the 0.35 air chanegs per hour for the living spaces is met with 45 cfm, but I'm sure we'd need more to account for the potential to exhaust more than this amount at any given time. Any other Canucks encountered this situation with the new Building code?

 

[AbbyNormal]

Do you have fuel fired appliances? Are they direct vent?

A clothes dryer to deal with as well.

Did an R2000 home quite some time back with a Jenn Aire range, envelope infitlration was insufficient make up. It alerted us to the fact that some traps were not primed.

Had to add a motorized damper interlocked with the Jenn air. The air dumped into a corner of the basement without any water pipes.

 

[WinniPEng]

There are no fuel-fired appliances - everything's electric.

The outside air intake is integral to the furnace, with the opening on the suction side of the fan, which is wired to run constantly.

And yes, there is a clothes dryer, which I neglected to mention earleir.

 

[Engineer6512]

Conisder using a Heat Recovery Ventilator (HRV) in each unit. Several manufacturers now make apartment sized units in the under 100 cfm range. Your steady state ventilation (both supply and exhaust) is taken care of by the unit. When a bathroom fan or exhaust fan is in use, extra air is allowed into the space since the supply air duct is always open. Apartment sized units are roughly $400.

 

[AbbyNormal]

HRV is a good way to ventilate for sure especially in Winterpeg.

HRVs drawing air from a couple bathrooms and the kitchen area is perhaps 30 cfm a shot and not the greatest for quick removal of odours. Would still put in bathroom fans myself.

HRV will not pressurize space and try to drive moist air out through a cold wall.

A motorized damper interlocked with a dryer or a range hood would be a passive negtive system. Cold air coming in not humid air going out.

HRV along with a fresh air duct to the return will end up pressurizing the space and the occupants retrofitting a humidifier after the first winter.

Need to resolve combusiton air requiremts first IMHO then deal with make up air. Direct vent makes life easier. The OP mentioned fan coil tho.

 

[AbbyNormal]

well electric heat you do not have to worry about back drafting.

Constant fan will feel pretty drafty when its 50 below at Portage and Main prairieboy. How about a dehumidistat opens a fresh air damper on a rise in RH. Maybe an air cycler control perhaps.

I did a lot of new construction 7 hours east of you. The first winter an HRV would work over timne drying out the moisture of construction. Second winter it was so dry their lips were cracking and they were adding humidifiers.

Maybe investigate an intermiottent ventialtion scheme, higher airflow but only when needed like a rise in RH or CO2.

My theory, people exhale moisture and CO2. Something that controls a rise in H2O indirectly controls CO2. No complaints from my worst hypochondriac customers with intermittent ventialtion keep the windows from condensating.

 

[AbbyNormal]

just teasing with the prairie boy,