In my experience, glass doesn't want to be a roof. Glass in a roof is
expensive, invites rain leaks, causes overheating, and may be damaged or
broken by thermal expansion and contraction. In summer, it's difficult, or
at least inconvenient, to install and operate shading devices for glazing
located on a roof.
Glass in a skylight can be satisfactory if the skylight is kept small--2
feet by 4 feet in English units, or smaller. We use them for daylighting
spaces like stairwells, entries, or bathrooms, or to boost the illumination
away from windows in large rooms.
In winter, vertical glass can transmit a high fraction of available
sunlight for warming; probably more than the spaces will actually need if
they are well-insulated. Even with some effective thermal mass, a building
with south-facing vertical glazing may still have to dump excess heat on
sunny winter days.
Vertical glass is much easier to manage in designing the house, and
certainly much less expensive to install and maintain.
In our region, we would advocate minimizing the heating loads with high
levels of insulation, effective air sealing and efficient windows. In a
building with very low heating requirements, not so much solar heating is
necessary, and can be achieved without roof glazing.
Best, Mike
Solar Bozo
>Does anybody have experience with calculating the heat impact on a glas roof?
>
>To get solar energy gains in winter, you have to design great glas windows
>and roofs to ahouse. The trouble on the other hand is the soar heat gain in
>summer - when you really not need it. So I am really interested in an easy
>way to calculate the thermal energy gain by a glas roof to minimize the
>shading systems or to avoid them by inclining the roof in the right angle and
>directing it to the right direction.
>
>The project I am thinking of is a simple one family home - so it should be a
>simple method.
>
>Uli Stehling, Darmstadt
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>This greenbuilding dialogue is sponsored by Oikos (www.oikos.com)
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__________________________________________________________________
This greenbuilding dialogue is sponsored by Oikos (www.oikos.com)
and Environmental Building News (www.ebuild.com). For instructions
send e-mail to greenbuilding-request@crest.org.
__________________________________________________________________