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Passive Heating and Cooling

MattRMagnum

Well-known member
Joined
May 10, 2012
Messages
225
Location
PNW
Hey Folks,

We've now relocated to a different part of the PNW, and I've a 36x60 workshop with an open loft in it. The building is wood-framed, and the exterior is metal.

We're wanting to turn the loft into my office next year, and the first step is trying to manage the temperature in there. I don't want to fully wall the office in, which leads me to trying to figure out how to heat/cool the whole building. I was thinking that adding gable vents would be a solid first step. Ideally some that can be adjusted, so I can open them in the summer, and close them in the winter. I'm hoping some passive heating/cooling like this will get me within the broad temperature range I want to be in, so then I can look into temperature controls for the office itself.

Who would I contact to install things like this? My fear of heights mean I won't be doing it, and the two garage builders I spoke to said they don't modify existing buildings. They only build new. Should I just keep calling around until I find someone?

I suppose the implied other question is: how much of a difference would gable vents like this make? We've a regular breeze, so I think they'll provide fairly constant airflow when open.
 
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egdede

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Joined
Dec 20, 2009
Messages
2,094
Are you in the rain-forest part of the PNW or the high-desert part?
 
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MattRMagnum

Well-known member
Joined
May 10, 2012
Messages
225
Location
PNW
Are you in the rain-forest part of the PNW or the high-desert part?
Neither? We live in western Washington, in farm land. A couple inches of snow in the winter (avg) and a heavy dose of heat/sunlight in the summer.
 

HoosierBuddy

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Joined
May 9, 2006
Messages
2,928
Location
Southern Indiana
I think windows and fans are the time proven way to lower the temperature inside a structure to a temperature near the outside temperature. You should be able to keep it within a degree or two with a moderate amount of airflow, but I think you'll want to do it at all levels, not just through gable vents to make it most effective.

Your last bit there, where you want to cool the whole garage passively, but also be able to have something for the office space contradicts your original statement about not wanting to wall your office in.

I think your best solution combines good airflow in the main building with a walled in, insulated office space. That walled in office space could then be heated and cooled with a mini-split which would give you heat in the winter and both cooling and dehumidification in the summer. If you're wanting more of an open feel, certainly you could use windows between the office and the garage.
 
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Jackfre

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Dec 26, 2010
Messages
4,411
Location
N CA
You might try a whole house fan. As it will cool off at night a good deal, set the fan to run overnight. It will help reduce the temp of the mass of the building several degrees. Before hiring anyone to do it, if the shop is in a secure location you could try running a couple box fans in windows to see how it might work. From what I hear you are facing the next few days it would be a good time to try it out.
 

Innovate1

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Joined
Jul 28, 2014
Messages
4,289
Location
Illinois near St. Louis, Missouri
Grew up in Oregon about 20 miles from the coast and lived in Bremerton for a few years so familiar with the climate (i.e. rain forest. :) ) Western Washington still leaves a fair amount of variation in climate but I am guessing you are in the Seattle to coast range area, east to west and not farther west like the Olympic area which is even wetter than where I grew up. (The local Lions Club held a rain derby where you could guess the rainfall that year and buy a ticket for $1 and the winner got a modest payout. They used it as a fund raiser for local high school college scholarships.) Humidity levels typically aren't too bad there. Contrary to what people might think the summers are pretty dry with most of the rainfall in the other seasons. I looked up Snoqualmie and see there is a heat warning. Dew point of 63 and high of 93 for today. We would think that's a pretty nice day where I live now! I know the area does get some higher humidity days but they are usually pretty limited. With the lower summer humidity the night time temps dip to low enough to generally get some night cooling. A whole house fan would work well if you could automate opening some inlets and turning it on when the conditions are right. Generally below 60 for dew point is considered comfortable for people based on studies so I generally only use night time ventilation when the dew point is 60 or lower but you may want to use a higher number. Roof insulation or probably even better would be a permanently ventilated area just under the roof so that the surface facing the inside is kept at near the outdoor air temp. That will help with keeping the daytime temps inside from rising due to roof heat.

Gable vents will help but to maximize benefit you need some wall insulation and some internal thermal mass with a way to ventilate when conditions outside are better than inside.
 

Denwood

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Joined
Sep 22, 2014
Messages
4,191
Location
Thunder Bay, Ontario, Canada
Passive convective cooling does work. You’ll need windows up high and at floor level. I did this using automated clerestory windows and a high capacity building exhaust fan. Windows and fan were automated using sensors from several Ecobee thermostats, and a Vera automation hub. Basically we precooled the building at night (9000 sq/ft, with commercial tenants). Windows were also automated during the day so AC would turn off and windows open if conditions were favourable.

At the basic level windows (or vents) at height used with windows ideally on the north side of the building (cooler) at ground level for intake is all you need. Stack effect cooling will do the rest. If nights in your area are hot/humid, this approach is not worth it.

If you have good air volume and decent mass, this will make a difference. We typically stayed off AC entirely in the building to about 1-2 pm if the building was able to precool at night.

This is a thread detailing that project: https://www.garagejournal.com/forum...ows-with-solar-smart-window-operators.329010/

We were able to drop temps about 10F in the building over night using just two automated windows and the building fan. Now keep in mind that this is not as efficient as the building exhaust fan exhausted on the main floor, pulling in cool air from 2nd story clerestory windows. It would have been more effective to blow air in on the main floor, exhausting hot air via the clerestory at night to take advantage of stack effect cooling (hot air rises).
 
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