METHOD AND SYSTEM FOR TESTING AIRTIGHTNESS OF A BUILDING ENVELOPE

• US 20180024025A1
• Filed: 02/08/2016
• Published: 01/25/2018
• Est. Priority Date: 02/09/2015
• Status: Active Grant

• Current Assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno
• Original Assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno
• Inventors: Phaff, Johan Cornelis, Borsboom, Wouter Antonius, Knoll, Bastiaan
• Granted Patent: US 10,545,067 B2
• Time in Patent Office: Days
• CPC Class Codes: G01F 1/34 by measuring pressure or differential pressure
• CPC Class Codes: G01M 3/26 by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors
• CPC Class Codes: G01M 3/2815 using pressure measurements
• CPC Class Codes: G01M 3/3236 by monitoring the interior space of the containers
• CPC Class Codes: G01M 3/3263 using a differential pressure detector G01M3/3245, G01M3/3272 take precedence
• CPC Class Codes: G01M 3/3272 for verifying the internal pressure of closed containers

Abstract

A method and system for testing airtightness of a building envelope (10). An air flow generator (21) is provided that is switchable between at least two different flow rates (Q0,Q1). The air flow generator (21) is repeatedly switched between a first flow rate (Q0) and a second flow rate (Q1) for modulating the building pressure (P1) as a function of time (t) between respective equilibrium pressure values at the first flow rate (Q0) and the second flow rate (Q1). The relative building pressure (ΔP) is measured by a differential pressure transducer (31) and recorded as a function of time (t). A pressure modulation amplitude (ΔPmodulation) is calculated for providing a measure of the airtightness.

Claims

1. A method for testing airtightness of a building envelope, the method comprising:

providing an air flow generator in a duct through the building envelope, wherein the air flow generator is switchable between at least two different flow rates;

providing a differential pressure transducer configured to measure a relative building pressure between a building pressure at the inside of the building envelope, and a reference pressure of a pressure container that is coupled to the differential pressure transducer;

repeatedly switching the air flow generator between a first flow rate and a second flow rate for modulating the building pressure as a function of time between respective equilibrium pressure values at the first flow rate and the second flow rate;

recording the relative building pressure as a function of time; and

calculating a pressure modulation amplitude of a time dependent measured value of the relative building pressure for providing a measure of the airtightness of the building envelope.

2. The method according to claim 1, wherein the air flow generator comprises an integrated ventilation system of the building envelope.

3. The method according to claim 1, wherein the first flow rate is obtained by switching off the air flow generator.

4. The method according to claim 3, wherein a comparative leakage flow rate f the building envelope is calculated based on the pressure modulation amplitude and a value of the second flow rate, wherein the comparative leakage flow rate is different from the second flow rate.

5. The method according to claim 4, wherein a comparative leakage flow rate (Qx) of the building envelope is based on a calculation of performed according to the equation:

Qx=Q1×

(Px/Δ

P_modulation)ⁿ,

where

Q1 is the second flow rate of the air flow generator,

Δ

P_modulation is the pressure modulation amplitude,

n is a pressure exponent of the building envelope, and

Px is a comparative pressure difference between an inside and an outside the building envelope for which the comparative leakage flow rate Qx is to be calculated, wherein Px is unequal to Δ

P_modulation.

6. The method according to claim 5, wherein the value of n is selected in a range between 0.58 and 0.72.

7. The method according to claim 4, wherein the comparative leakage flow rate is normalized by a floor area or surface area of the building envelope.

8. The method according to claim 1, wherein the recorded relative building pressure is fitted with a periodic step function, and

wherein the pressure modulation amplitude is calculated based on a difference between minimum and maximum values of the periodic step function.

9. The method according to claim 1, wherein the pressure container comprises a damped connection to surroundings of the pressure container for gradually equilibrating the reference pressure with the building pressure.

10. The method according to claim 9, wherein a respective time period in the first flow rate or the second flow rate between switching is shorter than an equilibration time constant with which the reference pressure equilibrates with the building pressure.

11. The method according to claim 10, wherein the pressure modulation amplitude is calculated taking into account the equilibration time constant for compensating pressure equilibration of the pressure container during a respective time period in the first flow rate or the second flow rate.

12. A non-transitory computer readable medium with program instructions for testing airtightness of a building envelope by:

providing an air flow generator in a duct through the building envelope, wherein the air flow generator is switchable between at least two different flow rates;

providing a differential pressure transducer configured to measure a relative building pressure between a building pressure at the inside of the building envelope, and a reference pressure of a pressure container that is coupled to the differential pressure transducer;

repeatedly switching the air flow generator between a first flow rate and a second flow rate for modulating the building pressure as a function of time between respective equilibrium pressure values at the first flow rate and the second flow rate;

recording the relative building pressure as a function of time; and

calculating a pressure modulation amplitude of a time dependent measured value of the relative building pressure for providing a measure of the airtightness of the building envelope

wherein the program instructions, when executed on a computer, cause the computer to carry out a method comprising;

receiving measurement values indicative of a modulated relative building pressure as a function of time;

calculating a pressure modulation amplitude of the time dependent relative building pressure; and

outputting a measure of the airtightness based on the pressure modulation amplitude.

13. The non-transitory computer readable medium according to claim 12, wherein the program instructions, when executed on a computer, cause the computer to

determine the switching of the air flow generator between the first flow rate and the second flow rate from the received measurement values.

14. A system for testing airtightness of a building envelope, the system comprising:

a differential pressure transducer configured to measure a relative building pressure as a function of time between;

a building pressure at the inside of the building envelope, and

a reference pressure of a pressure container that is coupled to the differential pressure transducer;

a non-transitory computer-readable memory configured to store the recorded relative building pressures and computer-executable instructions; and

a processor configured to execute the computer-executable instructions to perform a method comprising;

reading the stored relative building pressure from the non-transitory memory;

calculating a pressure modulation amplitude of the time dependent relative building pressure; and

output outputting a measure of the airtightness based on the pressure modulation amplitude.

15. The system according to claim 14 comprising:

an air flow generator in a duct through the building envelope, wherein the air flow generator is switchable between at least two different flow rates; and

a switch for repeatedly switching the air flow generator between a first flow rate and a second flow rate for modulating the building pressure as a function of time between respective equilibrium pressure values at the first flow rate and the second flow rate.