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Heating/Cooling 2nd Floor of Garage

We're building a story and a half detached garage that will have an office, craft studio, small guest space and bathroom upstairs. Trying to identify the best and most economical way to heat/cool a 22' x 24' space that is divided into 3 rooms plus a bathroom. This is space that will NOT be continuously occupied. Anyone have any suggestions?

Re: Heating/Cooling 2nd Floor of Garage

Use spray foam insulation on the underside of the roof decking to minimize the amount of heating/cooling load you need to handle. After that, you should really talk to the local heating/cooling contractors that may be installing it, as they can calculate the HVAC load and the proper sizing for a heatpump system to handle it. The good contractors should be able to tell you how much less you'll need depending on the insulation levels you choose, and how it varies depending on the # of people that may be in the building at any one time.

Ask them if they do geothermal heatpumps - they can greatly reduce the power usage over standard heatpumps, which can quickly pay back the extra install cost of drilling a well pipe for the geo lines (though with a rarely occupied building, the payback costs may be longer. But power costs are only going to increase in the future).

Re: Heating/Cooling 2nd Floor of Garage

How do you heat your house? Gas, oil, electric, wood, coal???

A forced-air system using the same fuel supply that you already have available would probably be your best--and most economical--choice. Although a geothermal heat pump would be very energy efficient, you would probably never see enough return to recoup the initial cost in a buliding that is only occupied part time.

Forced air would be favorable over radiant heat, since it would bring the temperature up from an unoccupied setting to an occupied setting more quickly.

Re: Heating/Cooling 2nd Floor of Garage

If you want to have a vent in each room I would go with a conventional forced air system, and while you are at it get them to price upstairs and downstairs. Most likely the unit that the hvac contractor installs will be big enough to cool upstairs & downstairs. I recently built this exact same size garage with an upstairs. I "think" a 1 ton unit handled all of it. It won't be very much more to do the whole thing.

If it's not going to be used alot you might be able to get away with a wall unit (hotel room style). I have used window units in a few garages that do heat and cooling . Instead of placing them in a window, I just recessed them in the wall. For $500-$600 (from Home Depot/Lowes) this is a inexpensive option if the unit is big enough to heat and cool the desired area. Also, I had a customer who got a steal on a hotel type hvac unit off of ebay. You might check there.

Good Luck.

Re: Heating/Cooling 2nd Floor of Garage

Well, you say that this will have an office and craft room. That in and of itself implies that someone will be working there often enough. So, depending on your geographical location, you really have alot of choices. I don't think Geothermal is you best option as the recovery time of a GeoT unit is quite long, so bringing the space up to temp or down, as the case may be, kind of negates the energy savings, as well as lengthens your ROI (Return On Investment). That being the case, you could use radiant heat in the slab of the garage, this makes warming the car on a cold winter morning that much quicker and melts all the snow off overnight, but also "precharges" the below and above with some heat. The radiant can then be extended into the ceiling/floor and Zoned to control individual room temps upstairs. You have MANY options of boilers and their efficiencies have GREATLY improved. Also, they will maintain temps at relatively low levels until you juice them up to warm the space when you know you will have company, and you can always set thermostats up on timers, so that if you use the space mostly on weekends, Friday night it will start to bring the upstairs to a comfortable level.

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