Recently, a webinar was organized, by TightVent Europe and AIVC on ‘Better Quantifying and Locating Building Leakages’. The panellist for the webinar were, Martin Prignon, UCLouvain, BE; Vitor Cardoso, FEUP, PT and Benedikt Kölsch, DLR, DE. Each panellist presented a technical presentation on existing methods to measure the airtightness of individual buildings components.
Martin Prignon, UCLouvain, BE said, “The consequences faced by building occupants due to infiltration has an impact on energy health and comfort of the residents. The research in airtightness focused on energy results in a tremendous increase in several pressurization tests or blower door tests which helps improve airtightness, develop a national database and guidelines for architects and contractors on how to build airtight buildings.”
Martin added, “However, the fact that we promote fan pressurization test also had a couple of setbacks because the fan pasteurization test reports airtightness of 50 pascals. Assuming that leakage is uniformly distributed along the envelope. The problem here is that the consequences and the amount of filtration depend on leakage location and distribution.”
He further explained the Quantification of Building Component Airtightness and its pros and cons as follows:
Numerical models – Airflow estimation through the development of fundamental equations of fluid mechanics.
PROS
- No planning constraints
- Easy interpolation of models
- Transferrable to larger models.
CONS
- Representation of reality
- Validation work needed
- Lack of crack data.
Laboratory testing – Measurement of ∆𝑝 – 𝑞 relation of the component in a highly controlled environment.
PROS
- No planning constraints
- Control of variables
- Visualisation of the component.
CONS
- Not “real configuration”: Component alone and No dust, enough space, etc.
- In-situ testing – Measurement of ∆𝑝 – 𝑞 relation of the component directly on site.
- PROS
- Real configuration (i.e., includes workmanship quality).
CONS
- Planning constraints
- Uncontrolled environment.
Vitor Emanuel Martins Cardoso, Doctoral Program, Civil Engineering presented a technical presentation on the uncertainty of effective leakage areas determination-reductive sealing technique. He also explained three different regression models, OLS – Ordinary least squares, OLS Uncertainty – Ordinary least squares uncertainty and WLOC – Weighted Line of Organic Correlation, their application and best practices.
Vitor said, “Dealing with air filtration besides weather, terrain and shielding data building details and ventilation strategies are important in modelling exchange rates, air movements, energy demand and this all make part of a decision and provide feedback to these variables.”
Effective leakage areas data is received, from the treatment of tightness measurements with fine pressurization. It represents the area of single orbitals that produce the same leakage as a group of leakages at the reference pressure difference. It is dependent on airflow, pressure difference and temperature. The typical form of expressing air leakage characteristics of building components or whole envelopes available extensively in ASHRAE and AIVC documentation repeated measurements and compilation of laboratory and in situ experiments. Results using ordinary least squares regression in the airflow and no propagation of uncertainty in incremental sealing.
Vitor added, “Reductive sealing LFC Offsetting results from blower door tests to attain the performance of individual elements or groups.” For example, the French database has 46 subcategories of leaks.
Martin explained the equation of Direct testing of building components with the help of an experimental setup. The direct component test measures in-situ 𝑛 and 𝐶 values of building components with high reliability (between 3% and 10%, depending on the chamber design).
But they must be replicated when measuring multiple components, it requires different pressure chambers depending on the component measured and uses another equipment than the fan pressurisation test. The application promises guarantee of a good installation, intermediate testing earlier in the construction process and improved databases with reliable in-situ values including 𝑛.
Benedikt Kölsch German Aerospace Center (DLR) – Institute of Solar Research Jülich, Germany discuss a new method for the single air leakage evaluation.
Benedikt said, “Uncontrolled airflow leads to increase consumption of heating and cooling energy. The most prominent method of measuring airtightness is Blower door test which has three purposes measuring air leakage in buildings, comparing relative airtightness of different buildings and determining the reduction of air permeability. But leak detection is time-consuming and expensive depending upon the inspection who’s doing the measurements and quantification of single leaks is very cumbersome in buildings. So, we are going to implement to investigate supplementary methods for the leak quantification but we will still have these broader tests as a subsequent, analysis and as a comparison in this presentation.”
Using Acoustics-
Sound takes predominantly the same paths as air in the fan pressurization method. So, it can be applied while the building is in use, independent from pressure or temperature differences and microphone arrays may localize leakage spots. He explained the same with a laboratory test apparatus in which 43 different leak configurations were tested identifying the distinction between different leak sizes possible. Its analysing the potential for localization of leaks using acoustics.
