This is a modern, elegant sunspace design from Architect William
Sikora.
As with most low thermal mass sunspaces, it does a good job of
providing heat to the house, but also serves other functions -- a true
multi-purpose space.
Thanks very much to William for providing the
description!
Description from William
This family designed and built energy efficient home was constructed north of
Minneapolis in 2010.It has an open plan with 900 sq ft of
finished area on the main floor, a 400 sq ft open loft and attached 450 sq ft
heated garage.Exterior walls are cement board clad rain
screen vented through the roof and furred out with rigid insulation on the
inside before drywall was applied.Exterior walls are R39 and
the metal clad roof is R56.The main heat source is a sand
bed heat storage system with an electric off peak boiler.No
other heat sources are used.
Click on pictures for fullsize
The design goal for this home was simplicity - as few moving parts as
possible, nothing too high tech and everything must be built, serviceable and
repairable by the owner with ordinary tools.
A two story low mass sun space is attached to the south side with both floors
accessible.The upper floor can be used for sunbathing in
Minnesota during a sunny winter day, clothes drying, wood drying or storage for
items not affected by heat.Twin wall, 8mm polycarbonate was
used for exterior glazing and interior and exterior railings.
Heated, filtered air from the sunspace is blown into the loft of the
home and pushed down with ceiling fans. Controls are simple – a line voltage
cooling thermostat in the sunspace and a line voltage heating thermostat on the
inside of the house. When both thermostats are closed, the 260 cfm blower
starts. Cool air enters the sunspace from the house through a one way damper .
Summer overheating is reduced by opening the upper and lower access doors.
Temperatures recorded on December 1, 2012 in Degrees F
Time
House
SunSpace
Ambient
8:00 am
68.4
15
10
9:00 am
68.4
42
10
10:00 am
68
54
12
11:00 am
68.2
79
15
12:00 pm
68.9
88.3
(Blower on)
19
1:00 pm
69.4
89.6
21
2:00 pm
69.4
87.8
22
3:00 pm
68.9
75(Blower off)
21
4:00 pm
67.8
70.5
21
5:00 pm
67.1
59.4
19
6:00 pm
66.7
50.7
18
It is obvious that the sunspace is not perfectly mass-less as shown by
interior temperatures after sunset at 4:30 PM.It can also be
noted that the sun does not completely strike the sunspace until about 10:00 am
due to trees on the south.The home’s heating system was not
in use during these readings.Interior stagnation
temperatures in the sunspace will reach 120 deg. with the blower off.Interior drywall and concrete floor provides enough of a thermal mass to
prevent overheating in the house.As the sun gets higher and
clears the trees to the south, the blower will run into the evening or as long
as the home requires heat.
Heating Cost 2011-2012
Month
KW Hours
Used for Heat Only
KW Hour
Cost
Cost
BTU
Sept
No heat
required
$.04
$0
0
Oct
400
$.04
$16
1,365,000
Nov
1200
$.04
$48
4,094,000
Dec
1750
$.04
$70
5,971,000
Jan
2350
$.04
$94
8,018,000
Feb
2000
$.04
$80
6,824,000
Mar
1250
$.04
$50
4,265,000
Apr
No heat
required
$.04
$0
0
Totals
8950 KWH
$358
30,537,000
It can be noted that 2011-2012 was a warm winter with 6,000 degree days
rather than the average 8,000 days but it was also much cloudier.
