re: solar gain for sunroom addition
12 nov 2003
>we are adding a 16 x 34 sunroom addition to the west side of our home.
bad news. less solar gain late in the day in wintertime, and overheating
in summertime. how about elongating it in the west direction and moving it
down to the south edge of the house?
>the 34 foot wall will be west facing and will be glazed with 3 6 foot
>insulated sliding patio doors and 2 36" x 54"... windows.
>north wall will have 3 36" x 54"...windows.
>...south wall glazing will be...1 6 foot patio door and... 1 36x54 window.
>it will be slab on grade with slate/ceramic tile flooring.
bad news. better to let warm air flow into the main house during the day and
minimize thermal mass in the sunspace, so it can get cold at night.
>...the 2nd story means no direct sunlight into the room until mid-morning.
>we can't extend the house's existing ductwork into the addition, so my
>delimina is how to heat and cool. the main house has a gas furnace
>located in the attic and central air from an outside unit. for
>cooling the addition, we have decided to have an 18,000 btu
>window/wall a/c mounted into the north wall.
how much will this "sunroom" add to the energy consumption of your house?
what will you do when the 18,000 btu runs out?
>with that much glass, i hope it will heat itself on most sunny winter days...
sounds like a plan.
>any websites to help compute expected solar gain from this addition?
nrel says 1130 btu/ft^2 of sun falls on a south wall and 510 and 220 fall
on west and north walls in raleigh on an average 38.9 f january day. in
july, 750 falls on a south wall, with 1010 and 600 on west and north on
an average 78.1 f day with a 68.1 and 88.0 average daily min and max and
humidity ratio w = 0.0149 pounds of water per pound of dry air.
>any comments on plans or possible pitfalls?
forget the ac. unroll 92% shadecloth over the west glazing in summertime,
and cool the space with that 68 f night air... ventilate during the day
if it ever gets warmer than the outdoors.