4 ms·

I wonder if it makes sense to work these formulas by region. When people discuss that roofs need to be white I would think that only applies when cooling domina

I wonder if it makes sense to work these formulas by region. When people discuss that roofs need to be white I would think that only applies when cooling dominates energy use. It seems where heating is dominate should have black roofs.

KiranRao0 4y ago
While I agree, often times the places that need the most heat are those with snow. So it may still be better to optimize for cooling in many cases.
- detourdog 4y ago
  Maybe but I can tell that is not my case. If I was to generalize my question beyond my circumstances it would. What coatings should be used for roof and exterior walls for a well insulated building in in the mid forties latitude. Snow has some insulating value so the heatloss is reduced. A highly absorbent roof might still be a plus. I'm currently trying to figure out the if I can put a thin layer of phase change material PCM on my exterior walls. The idea would be that the phase change would delay the reaction of the heat transmission through the walls. The building has a high thermal mass and it takes about 72 hours of a 15+ degree temperature difference to result in 4 degree temperature change of the interior of the building. Modern commercial buildings can't use open windows for ventilation. The ventilation has to be provided by a mechanical system. I'm trying to optimize the building to maintain a consistent overall temperature range of 72-78 degrees. The summer is not a problem the heat pumps and solar array mean I only get 5 electric bills a year. I think that I can do a lot of optimization of coatings and solar thermal to get to net zero.
coryrc 4y ago
Slightly warmer attic in winter doesn't reduce heat loss significantly, but in summer the roof temperature increase is much greater than winter, does measurably increase cooling load in insufficiently insulated houses, and, in aggregate, causes the Urban Heat Island Effect along with road surfaces.
- detourdog 4y ago
  Currently most of the insulation I have installed in the attic is in the rafters of the ceiling. probably close to 18" of high density cellulose. The fire sprinkler system is dry. I could add another layer of insulation in the roof rafters or not. The building is from 1931 and I added the sprinkler and more insulation in the attic. My heating load is much greater than my cooling load. Most of the other points don't apply to my situation.
  - coryrc 4y ago
    https://www.greenbuildingadvisor.com/article/creating-a-conditioned-attic https://www.greenbuildingadvisor.com/article/creating-a-cond...
schiffern 4y ago
I think the person you replied to knows that, hence why they said >> choose a coating to minimize energy use for the building in whatever climate surrounds it
- detourdog 4y ago
  Yes, their point of view seemed the most nuanced and that is why I asked them. I wasn't challenging them. I was hoping for more thoughts.

KiranRao0 4y ago

While I agree, often times the places that need the most heat are those with snow. So it may still be better to optimize for cooling in many cases.

detourdog 4y ago
Maybe but I can tell that is not my case. If I was to generalize my question beyond my circumstances it would. What coatings should be used for roof and exterior walls for a well insulated building in in the mid forties latitude. Snow has some insulating value so the heatloss is reduced. A highly absorbent roof might still be a plus. I'm currently trying to figure out the if I can put a thin layer of phase change material PCM on my exterior walls. The idea would be that the phase change would delay the reaction of the heat transmission through the walls. The building has a high thermal mass and it takes about 72 hours of a 15+ degree temperature difference to result in 4 degree temperature change of the interior of the building. Modern commercial buildings can't use open windows for ventilation. The ventilation has to be provided by a mechanical system. I'm trying to optimize the building to maintain a consistent overall temperature range of 72-78 degrees. The summer is not a problem the heat pumps and solar array mean I only get 5 electric bills a year. I think that I can do a lot of optimization of coatings and solar thermal to get to net zero.

coryrc 4y ago

Slightly warmer attic in winter doesn't reduce heat loss significantly, but in summer the roof temperature increase is much greater than winter, does measurably increase cooling load in insufficiently insulated houses, and, in aggregate, causes the Urban Heat Island Effect along with road surfaces.

detourdog 4y ago
Currently most of the insulation I have installed in the attic is in the rafters of the ceiling. probably close to 18" of high density cellulose. The fire sprinkler system is dry. I could add another layer of insulation in the roof rafters or not. The building is from 1931 and I added the sprinkler and more insulation in the attic. My heating load is much greater than my cooling load. Most of the other points don't apply to my situation.
- coryrc 4y ago
  https://www.greenbuildingadvisor.com/article/creating-a-conditioned-attic https://www.greenbuildingadvisor.com/article/creating-a-cond...

schiffern 4y ago

I think the person you replied to knows that, hence why they said >> choose a coating to minimize energy use for the building in whatever climate surrounds it

detourdog 4y ago
Yes, their point of view seemed the most nuanced and that is why I asked them. I wasn't challenging them. I was hoping for more thoughts.