System and method for determining infiltration of a building through empirical testing using a CO2 concentration monitoring device

• US 10,156,554 B1
• Filed: 04/25/2016
• Issued: 12/18/2018
• Est. Priority Date: 02/25/2015
• Status: Active Grant

• Current Assignee: Clean Power Research LLC
• Original Assignee: Clean Power Research LLC
• Inventors: Hoff, Thomas E.
• Primary Examiner(s): Craig, Dwin M
• Application Number:
  US15/138,049
• Time in Patent Office: 967 Days
• Field of Search: 703 2
• CPC Class Codes: G01N 33/004 for CO, CO2
• CPC Class Codes: G01N 33/0062 concerning the measuring method, e.g. intermittent, or the display, e.g. digital
• CPC Class Codes: G01N 33/0075 for multiple spatially distributed sensors, e.g. for environmental monitoring transmission systems for measured values G08C
• CPC Class Codes: G06F 17/18 for evaluating statistical data , e.g. average values, frequency distributions, probability functions, regression analysis forecasting specially adapted for a specific administrative, business or logistic context G06Q10/04
• CPC Class Codes: G06F 2111/10 Numerical modelling
• CPC Class Codes: G06F 30/20 Design optimisation, verification or simulation optimisation, verification or simulation of circuit designs G06F30/30
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

A building loses or gains heat through its envelope based on the differential between the indoor and outdoor temperatures. The losses or gains are due to conduction and infiltration. Conventionally, these effects are typically estimated by performing an on-site energy audit. However, total thermal conductivity, conduction, and infiltration can be determined empirically. The number of air changes per hour are empirically measured using a CO₂ concentration monitoring device, which enables the infiltration component of total thermal conductivity to be measured directly. The conduction component of thermal conductivity can then be determined by subtracting the infiltration component from the building'"'"'s total thermal conductivity.

Claims

1. A system for determining infiltration of a building through empirical testing using a CO₂ concentration monitoring device, comprising:

a CO₂ concentration monitoring device provided inside a building under test and operable to determine and record initial CO₂ concentration, and further operable to measure and record further CO₂ concentrations inside the building subsequent to an increase in CO₂ concentration over the initial CO₂ concentration and a negation of sources causing the increase in the CO₂ concentration inside the building until the further CO₂ concentrations stabilize; and

a computer comprising a processor configured to execute code in a memory, the code comprising;

a baseline CO₂ concentration applicable to outside the building;

a total thermal conductivity of the building;

an infiltration module configured to determine infiltration of the building based on a number of air changes as a function of the difference of the initial CO₂ concentration less the baseline CO₂ concentration over one or more of the further CO₂ concentration at a given time less the baseline CO₂ concentration and the given time; and

a conduction module configured to determine conduction of the building as the difference of the total thermal conductivity less the infiltration of the building, wherein at least one improvement to a shell of the building is performed based on the infiltration and the conduction.

2. A system according to claim 1, wherein the number of air changes n is determined in accordance with:

3. A system according to claim 1, further comprising:

the infiltration module further configured to limit the further CO₂ concentrations as recorded during the test by the CO₂ concentration monitoring device to an upper bound indoor CO₂ concentration,

wherein the upper bound indoor CO₂ concentration was measured under steady-state, fully-occupied conditions inside the building.

4. A system according to claim 3, wherein the upper bound indoor CO₂ concentration ┌

C_t^Inside┐

at time t expressed in hours is determined in accordance with;

5. A system according to claim 1, further comprising:

the infiltration module further configured to determine the infiltration of the building based on a number of air changes as a function of steady-state, fully-occupied conditions inside the building.

6. A system according to claim 5, wherein the number of air changes n is determined in accordance with:

7. A system according to claim 1,

wherein the CO₂ concentration monitoring device is remotely interfaced to the computer.

8. A system according to claim 1, further comprising:

a testing ensemble configured to find the total thermal conductivity, thermal mass, and effective window area for the building through a series of sequentially-performed empirical tests, each successive empirical test building on findings of the earlier empirical tests.

9. A system according to claim 1, the baseline CO₂ concentration further comprising at least one of:

prior to measuring and recording the further CO₂ concentrations, the CO₂ concentration monitoring device outside the building being operable to be calibrated and further operable to record the CO₂ concentration upon completion of the calibration as the baseline CO₂ concentration;

a plurality of CO₂ concentration monitoring devices, one of which is operable to measure and record the further CO₂ concentrations and the other of which being operable to record the CO₂ concentration outside the building as the baseline CO₂ concentration; and

the baseline CO₂ concentration assumed to be 400 ppm.

10. A system according to claim 1, the increase in CO₂ concentration further comprising at least one of:

one or more people being introduced into the building;

a known quantity of dry ice being converted into a gaseous form inside the building; and

a CO₂ fire extinguisher of known capacity being discharged inside the building.

18. A method according to claim 1, further comprising the step of:

finding the total thermal conductivity, thermal mass, and effective window area for the building through a series of sequentially-performed empirical tests, each successive empirical test building on findings of the earlier empirical tests.

11. A method for determining infiltration of a building through empirical testing using a CO₂ concentration monitoring device, comprising the steps of:

choosing by a computer comprising a processor a baseline CO₂ concentration outside a building under test;

obtaining by the computer a total thermal conductivity of the building;

determining and recording initial CO₂ concentration inside the building using a CO₂ concentration monitoring device;

increasing CO₂ concentration over the initial CO₂ concentration;

negating sources causing increase in the CO₂ concentration inside the building and thereafter measuring and recording further CO₂ concentrations inside the building using the CO₂ concentration monitoring device until the further CO₂ concentrations stabilize;

determining by the computer infiltration of the building based on a number of air changes as a function of the difference of the initial CO₂ concentration less the baseline CO₂ concentration over one or more of the further CO₂ concentration at a given time less the baseline CO₂ concentration and the given time; and

determining by the computer conduction of the building as the difference of the total thermal conductivity less the infiltration of the building, wherein at least one improvement to a shell of the building is performed based on the infiltration and the conduction.

12. A method according to claim 11, wherein the number of air changes n is determined in accordance with:

13. A method according to claim 11, further comprising the step of:

limiting the further CO₂ concentrations as recorded during the test by the CO₂ concentration monitoring device to an upper bound indoor CO₂ concentration,

wherein the upper bound indoor CO₂ concentration was measured under steady-state, fully-occupied conditions inside the building.

14. A method according to claim 13, wherein the upper bound indoor CO₂ concentration ┌

C_t^Inside┐

at time t expressed in hours is determined in accordance with;

15. A method according to claim 11, further comprising the step of:

determining the infiltration of the building based on a number of air changes as a function of steady-state, fully-occupied conditions inside the building.

16. A method according to claim 15, wherein the number of air changes n is determined in accordance with:

17. A method according to claim 11,

wherein the CO₂ concentration monitoring device is remotely interfaced to the computer.

19. A method according to claim 11, the step of choosing the baseline CO₂ concentration further comprising at least one of the steps of:

prior to measuring and recording the further CO₂ concentrations, calibrating the CO₂ concentration monitoring device outside the building and recording the CO₂ concentration upon completion of the calibration as the baseline CO₂ concentration;

calibrating a plurality of CO₂ concentration monitoring devices, one of which measuring and recording the further CO₂ concentrations and the other of which recording the CO₂ concentration outside the building as the baseline CO₂ concentration; and

assuming the baseline CO₂ concentration to be 400 ppm.

20. A method according to claim 11, the step of increasing CO₂ concentration further comprising at least one of the steps of:

introducing one or more people into the building;

converting a known quantity of dry ice into a gaseous form inside the building; and

discharging a CO₂ fire extinguisher of known capacity inside the building.