System and method for empirical electrical-space-heating-based estimation of overall thermal performance of a building
The overall thermal performance of a building UA Total can be empirically estimated through a short-duration controlled test. Preferably, the controlled test is performed at night during the winter. A heating source is turned off after the indoor temperature has stabilized. After an extended period, such as 12 hours, the heating source is briefly turned back on, such as for an hour, then turned off. The indoor temperature is allowed to stabilize. The energy consumed within the building during the test period is assumed to equal internal heat gains. Overall thermal performance is estimated by balancing the heat gained with the heat lost during the test period.
1. A system for empirical electrical-space-heating-based estimation of overall thermal performance of a building the aid of a digital computer, comprising:
a non-transitory computer readable storage medium comprising program code;
a thermometer located inside a building;
a thermometer located outside of the building;
at least one portable electric space heater located inside the building and configured to:
stop operating at the beginning of an unheated period;
resume operating at the end of the unheated period and continue operating for a duration of a heated period;
stop operating at the end of the heated period;
a computer processor interfaced to the storage medium, wherein the computer processor is configured to execute the program code to perform steps to:
record into the storage medium a baseline indoor temperature taken by the indoor thermometer and a baseline outdoor temperature taken by the outdoor thermometer prior to the stop of the operation of the at least one portable electric space heater at the beginning of the unheated period;
record into the storage medium a starting indoor temperature taken by the indoor thermometer at the end of the unheated period prior to the resumption of the operation of the at least one portable electric space heater;
record into the storage medium a final indoor temperature from taken by the indoor thermometer after a stabilizing period following the heated period;
measure energy consumed in the building from the beginning of the unheated period to the ending of the stabilizing period as equaling heat gained inside the building from internal sources of heat;
estimate an expected final indoor temperature at the end of the stabilizing period based on the at least one portable electric space heater not having been run for the heated period;
determine the heat gained inside the building over the heated period through operation of the portable electric space heater using the electricity requirements of the at least one portable electric space heater, the baseline indoor temperature, the final indoor temperature, the expected final indoor temperature, and the duration the heated period in accordance with:
Q
Heat
Delivered
-
Furnace
=
(
R
Furnace
)
(
t
2
-
t
1
)
(
T
0
-
T
3
No
Heat
T
3
-
T
3
No
Heat
)
where Q Heat Delivered-Furnace is the heat gained inside the building by the at least one portable electric space heater having operated for the heated period, R Furnace are the electricity requirements of the portable electric space heater, t 1 is the starting time of the heated period, t 2 is the ending time of the heated period, T 0 is the baseline indoor temperature, T 3 is the final indoor temperature, T 3 No Heater is the expected final indoor temperature; and
estimate overall thermal performance of the building using the heat gained through using the at least one portable electric space heater, the measured energy, the indoor temperatures, the baseline outdoor temperature, and the estimated final indoor temperature.
2. A system according to claim 1 , wherein the computer processor is wirelessly interfaced to the at least one portable electric space heater and controls the operations of the portable electric space heater.
3. A system according to claim 1 , wherein the computer processor is wirelessly interfaced to the thermometer inside the building and the thermometer outside the building.
4. A system according to claim 1 , wherein the computer processor is further configured to execute the program code to perform steps to:
use the overall thermal performance of the building to analyze one or more potential energy investments into the building, wherein at least one of the energy investments is performed based on the analysis.
5. A system according to claim 4 , wherein the potential energy investments affect only a portion of the building's envelope by changing that portion's conduction.
6. A system according to claim 5 , wherein the computer processor is further configured to execute the program code to perform steps to:
evaluate a change to the overall thermal performance of the building if the potential energy investments are performed.
7. A system according to claim 6 , wherein the changed overall thermal performance is evaluated in accordance with the equation:
Total
=
UA
Total
+
∑
j
=
1
M
(
U
j
-
U
^
j
)
A
j
where the is the changed overall thermal performance, UA Total is the overall thermal performance, M is a number of the energy investments being performed on the envelope, U j and Û j respectively represent existing and proposed U-values of surface j comprised in the envelope, and A j represents the surface area of surface j.
8. A system according to claim 6 , wherein the potential energy investments also affect the overall thermal performance by changing the infiltration of the building's envelope by air.
9. A system according to claim 8 , wherein the changed overall thermal performance is evaluated in accordance with the equation:
Total
=
UA
Total
+
∑
j
=
1
M
(
U
j
-
U
^
j
)
A
j
+
ρ
c
(
n
-
n
^
)
V
wherein the Total is the changed overall thermal performance, UA Total is the overall thermal performance, M is a number of the energy investments being performed on the envelope, U j and Û j respectively represent existing and proposed U-values of surface j comprised in the envelope, A j represents the surface area of surface j, ρ is the density of the air, c is the specific heat of the air, n is the number of air changes per hour before the energy investments are performed, {circumflex over (n)} is the number of air changes per hour after the energy investments are performed, and V is the volume of the air per the air change.
10. A method for empirical electrical-space-heating-based estimation of overall thermal performance of a building the aid of a digital computer, comprising:
providing a non-transitory computer readable storage medium comprising program code;
providing a thermometer located inside a building;
providing a thermometer located outside of the building;
using at least one portable electric space heater located inside the building, comprising:
stopping operations of the portable electric space heater at the beginning of an unheated period;
resuming operating the portable electric space heater at the end of the unheated period and continuing operating the portable electric space heater for a duration of a heated period;
stopping the operations of the portable electric space heater at the end of the heated period;
providing a computer processor interfaced to the storage medium, wherein the computer processor is configured to execute the program code;
recording with the computer processor into the storage medium a baseline indoor temperature taken by the indoor thermometer and a baseline outdoor temperature taken by the outdoor thermometer prior to the stop of the operation of the at least one portable electric space heater at the beginning of the unheated period;
recording with the computer processor into the storage medium a starting indoor temperature taken by the indoor thermometer at the end of the unheated period prior to the resumption of the operation of the at least one portable electric space heater;
recording with the computer processor into the storage medium a final indoor temperature from taken by the indoor thermometer after a stabilizing period following the heated period;
measuring with the computer processor energy consumed in the building from the beginning of the unheated period to the ending of the stabilizing period as equaling heat gained inside the building from internal sources of heat;
estimating with the computer processor an expected final indoor temperature at the end of the stabilizing period based on the at least one portable electric space heater not having been run for the heated period;
determining with the computer processor the heat gained inside the building over the heated period through operation of the portable electric space heater using the electricity requirements of the at least one portable electric space heater, the baseline indoor temperature, the final indoor temperature, the expected final indoor temperature, and the duration the heated period; and
estimating with the computer processor overall thermal performance of the building using the heat gained through using the at least one portable electric space heater, the measured energy, the indoor temperatures, the baseline outdoor temperature, and the estimated final indoor temperature; and
using with the computer processor the overall thermal performance of the building to analyze one or more potential energy investments into the building, wherein at least one of the energy investments is performed based on the analysis, wherein the potential energy investments affect only a portion of the building's envelope by changing that portion's conduction;
evaluating with the computer processor a change to the overall thermal performance of the building if the potential energy investments are performed, wherein the changed overall thermal performance is evaluated in accordance with
Total
=
U
A
Total
+
∑
j
=
1
M
(
U
j
-
U
^
j
)
A
j
where the is the changed overall thermal performance, UA Total is the overall thermal performance, M is a number of the energy investments being performed on the envelope, U j and Û j respectively represent existing and proposed U-values of surface j comprised in the envelope, and A j represents the surface area of surface j.
11. A method according to claim 10 , wherein the heat gained inside the building over the heated period through operation of the at least one portable electric space heater is determined in accordance with:
Q
Heat
Delivered
-
Furnace
=
(
R
Furnace
)
(
t
2
-
t
1
)
(
T
0
-
T
3
No
Heat
T
3
-
T
3
No
Heat
)
where Q Heat Delivered-Furnace is the heat gained inside the building by the at least one portable electric space heater having operated for the heated period, R Furnace are the electricity requirements of the portable electric space heater, t 1 is the starting time of the heated period, t 2 is the ending time of the heated period, T 0 is the baseline indoor temperature, T 3 is the final indoor temperature, T 3 No Heater is the expected final indoor temperature.
12. A method according to claim 10 , wherein the computer processor is wirelessly interfaced to the at least one portable electric space heater and controls the operations of the portable electric space heater.
13. A method according to claim 10 , wherein the computer processor is wirelessly interfaced to the thermometer inside the building and the thermometer outside the building.
14. A method according to claim 10 , wherein the potential energy investments also affect the overall thermal performance by changing the infiltration of the building's envelope by air.
15. A method according to claim 14 , wherein the changed overall thermal performance is evaluated in accordance with the equation:
Total
=
UA
Total
+
∑
j
=
1
M
(
U
j
-
U
^
j
)
A
j
+
ρ
c
(
n
-
n
^
)
V
wherein the Total is the changed overall thermal performance, UA Total is the overall thermal performance, M is a number of the energy investments being performed on the envelope, U j and Û j respectively represent existing and proposed U-values of surface j comprised in the envelope, A j represents the surface area of surface j, ρ is the density of the air, c is the specific heat of the air, n is the number of air changes per hour before the energy investments are performed, {circumflex over (n)} is the number of air changes per hour after the energy investments are performed, and V is the volume of the air per the air change.
16. A method for empirical electrical-space-heating-based building overall thermal performance estimation the aid of a digital computer, comprising:
providing a non-transitory computer readable storage medium comprising program code;
providing a thermometer located inside a building;
providing a thermometer located outside of the building;
using at least one portable electric space heater located inside the building, comprising:
stopping operations of the portable electric space heater at the beginning of an unheated period;
resuming operating the portable electric space heater at the end of the unheated period and continuing operating the portable electric space heater for a duration of a heated period;
stopping the operations of the portable electric space heater at the end of the heated period;
providing a computer processor interfaced to the storage medium, wherein the computer processor is configured to execute the program code;
recording with the computer processor into the storage medium a baseline indoor temperature taken by the indoor thermometer and a baseline outdoor temperature taken by the outdoor thermometer prior to the stop of the operation of the at least one portable electric space heater at the beginning of the unheated period;
recording with the computer processor into the storage medium a starting indoor temperature taken by the indoor thermometer at the end of the unheated period prior to the resumption of the operation of the at least one portable electric space heater;
recording with the computer processor into the storage medium a final indoor temperature from taken by the indoor thermometer after a stabilizing period following the heated period;
measuring with the computer processor energy consumed in the building from the beginning of the unheated period to the ending of the stabilizing period as equaling heat gained inside the building from internal sources of heat;
estimating with the computer processor an expected final indoor temperature at the end of the stabilizing period based on the at least one portable electric space heater not having been run for the heated period;
determining with the computer processor the heat gained inside the building over the heated period through operation of the portable electric space heater using the electricity requirements of the at least one portable electric space heater, the baseline indoor temperature, the final indoor temperature, the expected final indoor temperature, and the duration the heated period in accordance with:
Q
Heat
Delivered
-
Furnace
=
(
R
Furnace
)
(
t
2
-
t
1
)
(
T
0
-
T
3
No
Heat
T
3
-
T
3
No
Heat
)
where Q Heat Delivered-Furnace is the heat gained inside the building by the at least one portable electric space heater having operated for the heated period, R Furnace are the electricity requirements of the portable electric space heater, t 1 is the starting time of the heated period, t 2 is the ending time of the heated period, T 0 is the baseline indoor temperature, T 3 is the final indoor temperature, T 3 No Heater is the expected final indoor temperature; and
estimating with the computer processor overall thermal performance of the building using the heat gained through using the at least one portable electric space heater, the measured energy, the indoor temperatures, the baseline outdoor temperature, and the estimated final indoor temperature.