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Passive solar and natural light

Posted by Mavers (My Page) on
Tue, Mar 19, 13 at 20:16

Our house design has porches and porch roofs around the front and back of the house. The front door will be facing south-east, and thus, the back of the house (sliding doors) will face north-west.

When I posted our plans on the 'building a home' forum, I received feedback from a few people who thought the porches would really darken the house and we should consider removing them.

We live in South-Eastern Ontario, Canada and have put a lot of windows on the north-west wall because that is our lake view (yes, we realize that is not ideal in terms of passive solar design and heat loss!).

Any suggestions about how to make the design use passive solar energy more effectively on the front side of the house, and also any input on the porch roof at the rear of the house. Our GC seems to think that the difference in removing it would be negligible. The land behind our house slopes down and away, though there are a lot of trees all around the house.

Please help!!!

Follow-Up Postings:

RE: Passive solar and natural light

So your GC thinks that removing some of the covered porch in the back will be negligible in light gain? I would disagree. It would help a measurable amount with light gain in that portion of the house. As far as energy consequences, I agree with negligible.

As for Passive Solar input on the front, your current design will have close to zero benefit. South facing entrances on passive solar designs are the most challenging orientation to design for due to the need to eliminate shading (covered entrances or porches).

If youre serious about passive solar (free heating) then you could eliminate the jog in the family room, eliminate the front covered porch and increase the amount of glazing on the front of your house. You could leave a small amount of covered porch just at the front door, perhaps making it with a nicer finish like timber frame to compensate for the sacrifice in the bigger covered porch aesthetics.

The Kitchen, office and covered entry will make this challenging but could have some measurable benefits.

RE: Passive solar and natural light

Thanks Brian_Knight. Your input is much appreciated.

Another suggestion we have had is to leave the rear porch roof open with just the trusses (lanai?) to allow more light through. Any thoughts on that?


RE: Passive solar and natural light

We built, new, 3 years ago. We put a 10 foot wide covered porch around the entire main floor. It is the best thing we could have done! We are in central California, on the coast. Winters are around freezing at night, days in summer are in low 90's F. The house is 8500 sq ft of living space, and insulated to the max, including interior walls. We have an 18KW solar array - grid tied. Our electrical runs less than $50 per year, and propane is around $3000. The main floor has 10 foot high ceilings, with massive amounts of windows that are very high quality dual paned. We have very little heat loss or cold intrusion.

Just my 2 cents. It really depends on what is important to you!

RE: Passive solar and natural light

It really is an opinion based decision on how much covered porch is appropriate. The open trusses would certainly allow much more light into the interior and I think its a good choice. That decision should also be balanced with any possible increased maintenance needs of exposed wood/finishes.

I cant help but wonder if dancingsams wouldnt be happier with more light as opposed to more covered porch. Covered porches have a huge impact on light entering the interior. I think its rare that a wrap around porch is more beneficial than eliminating a portion of it for the gained lighting. Natural lighting is used all the time while outdoor living space around the entire home is used less so.

From an energy and comfort standpoint, covered porches are most beneficial on the East and West sides of the home.

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