HVAC Sizing for Concrete Homes

Gary Reecher

Here is a software for hvac sizing concrete homes

http://www.cement.org/bookstore/profile.asp?itemid=CD044

Have not used it.

Bob Eh?

Has anyone used this program?

How did it work out? I find that most loss programs seem to be all over the map when sizing low load homes and am looking for domething that has reasonably believable results........ Since I wish to use GHP and radiant these spreads amount to as much as 120% difference in cost due to heatpumps and slinky fields.

I would like to believe we are "Right Sizing"

Thanks

Steve Ebels_3

Concrete?

Are you talking about ICF construction?

Typically, a concrete house has a low air infiltration rate if you pay attention to the window and door openings. This is a good thing. Remember to incorporate a number for ventilation air in your air change per hour #.

Bob Eh?

This program claims it does ICF which is the target.....

I have been accounting for the air changes. Mind you most programs don't handle HRVs correctly (if at all). I think they fail to account that if you have 70* exit air and -30* inlet air that at 90% efficiency the net air temperature inbound is 15* (not 60*)......

JohnWood1

Try it thusly.......

When using the HRV and the loss program asks for ventilation air, use the complement of the efficiency of the hrv! If hrv is 80% eff, then use 20% of the vent rate of the unit in the program. Also on ICF, use a low infiltration factor. point 5 or even less. A tight ICF home could be as low as .3 ACH. If you are in a humid environ and figuring A/C, go on the light side as to capacity. If program says you need 38,456 round down! Comfort comes more from latent removal than sensible so a few degrees above the room setpoint at a low RH% is more comfortable than hitting it dead on and high RH.

rb_6

Demo

I'm trying out a copy for an upcoming article. Will keep you posted.