new home ideas - Page 4

 

Where, exactly? Got weather data? You might need some seasonal heat storage
for 100%-solar heat. I worked on an Irish house design that needed to store
summer heat for Nov-Feb, eg in a 20' tall x 24' diam insulated water tower
with a floating foamboard draindown cover under a transparent dome.

Energy Plus weather stats for Aberdeen (N 57):

       oct    nov    dec    jan    feb    mar

Tavg   9.0    6.1    4.2    3.6    4.3    5.6C
Hdir   1052   890    499    632    1141   1616  direct  |  Wh/m^2-day
Hglo   1314   652    314    448    1017   2107  global  |  of sun on
Hdiff  967    452    246    330    703    1402  diffuse |  the ground, vs

Hglo   3218   2145   1672   1956   2744   3785  global, for Phila, PA, USA

Phila is not a great solar heating climate, but it has about 3 times more
sun on the ground than Aberdeen in December.


Like this, viewed in a fixed font?

 ---------------------------------     ---------------------------------
|         |             |         |   |                                 |
|         |    garden   |         |   |           garden room           |
|         |             |         |   |                                 |
|         |     room    |         |   |---------------------------------|
|         |             |         |   |                                 |
|         |             |         |   |                                 |
|         |             |         |   |                                 |
|          -------------          |   |                                 |
|                                 |   |                                 |
|                                 |   |                                 |
|                                 |   |                                 |
|                                 |   |                                 |
|                                 |   |                                 |
|                                 |   |                                 |
|                                 |   |                                 |
|                                 |   |                                 |
|                                 |   |                                 |
|                                 |   |                                 |
|                                 |   |                                 |
|                                 |   |                                 |
 ---------------------------------     ---------------------------------
 
The one on the right can be less expensive and more efficient, with a lower
surface-to-volume ratio, without the south "wings." Garden rooms with plants
need to avoid freezing, but the ceilings might not need much insulation, if
they get cold at night.


What do you mean by that?


About 12", US R40, metric R7 (m^2C/W). A 16mx16mx2m tall airtight house with
R7 walls and ceiling and no windows(!) could have 16^2/7 = 36.6 W/C of ceiling
conductance + 128/7 = 18.3 for the walls, totaling 55. At 20C indoors and 5C
outdoors, it would only need (20-5)55 = 825 watts of heat, eg 200 watts from
4 half-time occupants + 625 watts from 625x24hx30d = 450 kWh/mo of indoor
electrical use. Maybe it doesn't need solar heat :-)


How about heating water in a big unpressurized tank with a $35 car radiator
and its 20 watt fans in the garden room, and making water for showers with
a $60 1"x300' 13-gallon plastic pressurized pipe coil in the 140 F tank?
 

A basement full of hot water would have a lower surface-to-volume ratio.
With no internal heat gains from people or their electrical use, you might
store 825Wx24hx30dx3mo = 1782 kWh in 1782/(60C-22C)/1.163 = 40 m^3 of water
cooling from 60 to 22 C in a 2mx10mx2m-tall tank lined with a single folded
piece of EPDM rubber roofing material.

Nick