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re: what would be the most energy efficient, safe, low maintenance house available today?
20 dec 1999
bill althouse althouse inc. wrote:
>> >the only way to do 100% solar heat without therpwhistles is...
>> >active gain-passive delivery + super insulation
>> bullshit. that's not the only way.
>it is the best way
that sounds more reasonable. it is not the only way to do 100% solar
house heating, but it is the best way, in your opinion. and you just
happen to sell such systems. but "it" is still rather vague...
btw, local architect jack althouse doesn't believe solar house heating
works in this philadelphia area, but won't trouble to understand it...
he designed a showcase "eco-house" for a high-energy high-school group
("students against violating the earth," aka s.a.v.e.) that has too many
windows, points in the wrong direction, and is mostly electrically heated.
it's full of real goods toys with placards explaining them, including an
expensive unused composting toilet and a black solar bag shower inside
the unsunny bathroom.
>> >roof integrated hot water collector...
>> that sounds a lot more expensive than a $1/ft^2 greenhouse sunspace
>> which adds floorspace to a house or a $1/ft^2 clear polycarbonate
>> roof (houses need roofs anyhow) with a 9 cent/ft^2 fixed trough
>> concentrator inside the attic...
>> >>>>clear roof trough is good thinking! any active source works fine
some are a lot more expensive than others. how much does your
"roof integrated hot water collector" cost per square foot,
including the roof itself, and how many square feet are needed?
you have a knack for avoiding questions, mr. althouse.
>> >connect active solar to radiant floor storage with 1 foot of sand
>> >wrapped in 2" extruded polystyrene.
>>
>> can you explain more? i can't quite picture this.
sounds like the top side of the sand is not "wrapped in foamboard."
>2" up inside of stem wall an 2" under the whole floor under 1 foot of sand
so the floor slab(?) has 1 foot of sand underneath, with a warm water pipe
snaking under the sand, and 2" of foamboard under the pipe, and 2" of
foamboard perimeter insulation, inside a footing (stemwall?) just a radiant
floorslab with some extra sand underneath to store more heat? i know of
similar wood-heated "solar" adirondack houses. where are your houses?
>> >...this thermodynamic flywheel effect stores enough energy to eliminate
>> >temperature swings in the house.
in my solar house heating experience (about 25 years), people who talk
about flywheels in houses don't usually understand thermodynamics. but
maybe you are an exception.
you are describing a system that stores solar heat in some thermal mass.
that requires changing its temperature, no? how can we store solar heat
in sand under the floor and also "eliminate temperature swings"? this
sounds like a house in which the occupants have to "live inside the heat
battery," and it sounds like it requires room temperature swings in order
to store heat. i don't see any way around that. am i confused...?
>> you mean the house overheats on a warm day? :-)
>
>not at all.
how can you avoid that, if storing heat in warm sand with a slowly-changing
temperature under the floor and a constant room temp above, with no way to
vary the rate of heatflow up through the floor? open some windows and
waste some solar heat?
>3 days heat is only a 2 degree change in room temp with a 5 degree
>icrease in floor temperature because of the volume of the mass and
>the radiant pipe is 6" under sand
that's a difficult sentence to take apart. you seem to be alluding to
a magical heat pulse traveling up through the sand. flywheels! :-)
can you be more articulate?
>> >temperature can be pegged to a 2 degree f differential in worst case-
>> >ie. no heat for a week.
>> more bullshit. let's see some numbers to prove it.
>our shell's between stud insulation peformance is twice fibreglass +r7 over
>the whole exterior to break thermal bridging...
sounds nice, albeit nonsensical. what's "twice fiberglass"? how much
fiberglass? what's the stud spacing? where are the numbers? what's
the actual thermal resistance of your wall, and the measured
house air infitration rate, with a blower door test?
>+with small r4 windows+ insulated door= 40,000 btus per day.
how small? how many? with what solar transmittance? pointing in which
directions? where is the house? what's the outdoor temp, and how much
sun does it get from each direction on an average december day? what's
the monthly electric bill? where do you get 40k btu/day. magic? :-)
sounds too small...
>12" of sand = 1200 cubic feetx100lbs per cubic
>foot=120,000lbs at a specific heat of .2btu /deg x 5 degree jump in sand temp
>when charged=120,000 btus or three days of 40,000 btus per day
more impenetrable prose. so this (single story?) house has 1200 ft^2
of floorspace? with what shape and dimensions and orientation? the
1993 ashrae hof says a pound of sand stores 0.191 btu/f and weighs
94.6 pounds per cubic foot, so raising 1200 ft^3 of sand 5 f requires
1200x94.6x0.191x5 = 108.4k btu, but how do you get the heat out of
the sand on a cloudy day without changing the room temperature?
>> >use bradford white combicor gas boiler-domestic hot water heater
>> >combination with internal heat exchanger($950) to interface
>> >radiant floor with collectors and domestic hotwater...
>> sounds like more than an "interface." a concentrating solar attic
>> can provide lots of hot water...
>> >...our system is 100% fraction and cozy without swings..
>> then why do you need the heater?
>100% fraction for space heat -dhw demand can have spikes when all the
>relatives come for a visit,or unreal cold snaps, and the unit it is
>an excellent interface
oh, the furnace is just for visiting relatives and unrealities.
perhaps you have a cozy gas-heated house...
>> and how much does it cost?
>much less than electic heat, and cheaper than gas- life cycle costed
and exactly how much is that?
nick
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