Mild climate - would you bother with passive solar design?

Discussion in 'Designing, building, making and powering your life' started by spud, Dec 8, 2014.

  1. spud

    spud Junior Member

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    The climate in which I am planning to build is coastal and fairly mild. The mid-winter average is 13 - 18 degrees Celsius. In summer it averages 19 - 25. It is generally quite humid.

    In such a climate is there much point in building a passive solar house?

    Most people around here seem to prefer to have big verandas (since outdoor living is so agreeable), but obviously a big covered veranda gets in the way of passive solar design, especially if your house is facing the equator (ie. north in the southern hemisphere).
     
  2. Grasshopper

    Grasshopper Senior Member

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    Im in the sub tropics similar temps to you, just a little higher
    Facing East with a open top balcony/veranda were we spend most of our time.
    Its a little hot to sit out there without shade even in winter.
    Im growing grapes over it, in the meantime I have a few shade sails.
    In winter it should be leafless and give me sun into the house through the windows and the rest of the time it gives me shade.
    On the coldest day if we get some sun in and close the curtains at dusk we stay pretty warm all night.
    Everyone here has covered verandas except me ,the guy who built this was an amateur astronomer and wanted the stars.(which is cool too)
     
  3. TLP

    TLP Junior Member

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    If you look at passive solar from a comfort perspective then yes it is worth it, although harsher climates with higher diurnal temperature swings will benefit more from lower energy cost. A mass system such as earth builds will regulate HVAC loads and keep the home from seeing hot and cold spots. Soil does a great job at this in combination with regulating humidity due to it's high ability to store-breath. Great thing about your climate zone is you have less a chance at screwing up the design and a home that over heats. There is alot to know about solar passive, some that try in hot climate zones don't take the time to learn. Then again, I have seen over insulated homes with little to no thermal mass via solar passive design over heat or experience high cooling loads since there is no mass for the heat to be absorbed.
     
  4. Brian Knight

    Brian Knight Junior Member

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    Its a great question and one that I think depends on if there is any other/backup heating system planned for. Sounds like your climate is too mild to bother but if there are times in the winter that you find yourself wishing for some more warmth, it would probably be worth the trouble to do some extra design and planning work.

    Passive solar design is usually thought of as a heating strategy but I feel the term could also include designing to exclude unwanted heat from the sun. In this case, the verandas you mention are a form of this passive solar design. Generally, deep east and especially west covered porches help to shade the walls, but more importantly the windows. Warm climates almost always benefit from big west overhangs or covered porches, low SHGC windows, and significant landscaping shade.

    Keeping these verandas or covered porches off the south side makes room for winter light to enter the home's windows. The south-facing, high SHGC window area to floor area is probably the most important variable to pay attention to and you would want to stick to the lower end of the range for most designs in warm climates.
     
  5. Brian Knight

    Brian Knight Junior Member

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    Woops, forgot this seems to be a southern hemisphere based forum so obviously substituting "north-facing" for "south-facing" would be the passive solar orientation of most importance. Ive been trying to modify my terminology to "sun-facing" to account for both hemisphere's winter sun direction.
     
  6. sweetpea

    sweetpea Junior Member

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    Hi, spud. I am in a mild coastal climate as well, and YES, passive solar is wonderful! Our coastal area is often damp from ocean mist and fog, and having the inside stay at a comfortable temperature, and even heat up to help stop any mold from forming is wonderful! We have thick insulation in walls, floors and ceiling, and the foundation is enclosed all the way to the ground, so the inside rarely gets below 50F/10C even if it's near freezing outside (which it could be sometimes in the early morning.) There are absolutely no trees for the whole length and ends of the long sunny wall. The shape of the house is a long, narrow building, so the rooms farthest away from the sunny wall will still get some heat.

    We have a cabin that is on low piers and even that amount of disconnect from the soil keeps it from being as warm as the connected foundation. We use thermal curtains to keep the heat in at night. Even on a chilly but sunny winter day outside, I can stand by the windows and feel the heat coming in. It's wonderful.

    The longest wall is facing the sunny side, with the living and dining areas are against that wall. That's where we spend the most time and want it to heat up first. We have large double-paned windows on the sunny side, but not the newest Low E windows, as they shut out too much heat. The windows are as tall as a person and about 1.3 meters wide, so the sun is on them early and is on them all day. The eaves over those windows are narrow, about 8 inches, which does not create shade as the sun moves across. There are more windows facing the sunset so the last of the heat comes in there.

    I am so pleased with the passive solar, it works better than I ever imagined. And with all the big windows, even on days when it is foggy, it is not depressingly dim inside. :)
     
  7. spud

    spud Junior Member

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    Great! Thanks all. I'm definitely going to design my home to include passive solar features (sun facing windows, etc.).
     

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