re: inexpensive retrofitting....
27 sep 2003
>i'm looking for ways to generate more heat in the house during the cold
>months, as well as ways to reduce the loss of heat... the house is over
>a hundred years old...
it may be very air-leaky. dry indoor air in the winter is one indication.
caulk a lot, and/or get a blower door test, or turn on a window exhaust fan
with the rest of the house windows and doors closed and walk around feeling
and watching (with a cigarette) for air leaks around windows, doorframes,
baseboards, air supply and return registers, and so on.
once it's airtight, you might add a sunspace on the south side to collect
warm air on sunny winter days, a shoebox with several 8'x8' sliding glass
doors, or less inexpensive polycarbonate glazing, or maybe cloudy poly film
over double 12' 1x3s bent into $2 bows with an 8' radius held together with
deck screws and 1x3 spacer blocks every 2'.
on 4' centers, 7 bows would make a 24'x8'x8' quarter-cylindrical space, with
top and middle and bottom purlins and a rebar ground stakes on 4' centers to
keep the bottom edge from moving. wrap the bottom purlin with poly film to
keep it from rotting and lay a foot of plastic film on the ground with some
gravel on top to reduce air leakage. you might attach a single $450 layer of
4'-wide 20-year replex clear polycarbonate with a spruce cap strip over each
bow, or attach a $20 16'x24' piece of 4-year greenhouse polyethylene film to
the end bows with 12' 1x3 cap strips.
let warm air circulate from the sunspace to the house via 2 pairs of 2'x4'
high and low vents or windows in the house wall with one-way passive plastic
film dampers. where i live, a sunspace like this would collect 0.9x8x24x1620
= 280k btu on an average january day and lose about 6h(80-30)12.5'x24'/r0.8
= 113k, for a net gain of 167k btu, about the same burning 2 gallons of oil.