Contaminant Transport through the Thermal Envelope – Evaluation of Airflows Based on Numerical Modeling and Field Measurements
Paper i proceeding, 2019

The overall aim of this project is to improve the methodology for finding the cause for indoor air problems in schools. The methodology is improved by providing methods for determining if the contaminant source is within the building envelope as well as understanding how the pressure distribution is affected by ventilation, climate and airtightness. There is an urgent need for an improved methodology since many schools in Sweden today have unexplained indoor air quality problems.

A numerical model has been developed that considers the influence that climate (wind speed, wind direction and temperature) and airtightness have on the air leakage in a building. The model is compared to measurements of pressure differences and weather data from a case study (a school building with documented indoor air problems). The analysis of the measurement at the school building shows that stack effect is an important parameter, even for a low-rise building. Wind pressure results in air flows both from and to the crawl space, primarily depending on wind direction combined with stack effect and air leakage distribution. Linear regression analysis of the measurement data proved to be a useful tool to detect anomalies in the measurements. A flow chart for an investigation procedure for air flows through the thermal envelope is presented in the paper.The overall aim of this project is to improve the methodology for finding the cause for indoor air problems in schools. The methodology is improved by providing methods for determining if the contaminant source is within the building envelope as well as understanding how the pressure distribution is affected by ventilation, climate and airtightness. There is an urgent need for an improved methodology since many schools in Sweden today have unexplained indoor air quality problems.

A numerical model has been developed that considers the influence that climate (wind speed, wind direction and temperature) and airtightness have on the air leakage in a building. The model is compared to measurements of pressure differences and weather data from a case study (a school building with documented indoor air problems). The analysis of the measurement at the school building shows that stack effect is an important parameter, even for a low-rise building. Wind pressure results in air flows both from and to the crawl space, primarily depending on wind direction combined with stack effect and air leakage distribution. Linear regression analysis of the measurement data proved to be a useful tool to detect anomalies in the measurements. A flow chart for an investigation procedure for air flows through the thermal envelope is presented in the paper.

pressure distribution

contaminant transport

air leakage

Författare

Fredrik Domhagen

Chalmers, Arkitektur och samhällsbyggnadsteknik, Byggnadsteknologi

Paula Wahlgren

Chalmers, Arkitektur och samhällsbyggnadsteknik, Byggnadsteknologi

Carl-Eric Hagentoft

Chalmers, Arkitektur och samhällsbyggnadsteknik, Byggnadsteknologi

14th International Conference on Thermal Performance of the Exterior Envelope of Whole Buildings

14th International Conference on Thermal Performance of the Exterior Envelope of Whole Buildings
Clearwater beach, FL, USA,

Förbättring av innemiljökvalitet i skolor med focus på transport av föroreningar från klimatskalet med hänsyn till interaktionen med ventilationssystemet

Formas, 2016-01-01 -- 2019-12-31.

Drivkrafter

Hållbar utveckling

Styrkeområden

Building Futures (2010-2018)

Hälsa och teknik

Ämneskategorier

Annan samhällsbyggnadsteknik

Strömningsmekanik och akustik

Husbyggnad

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Senast uppdaterat

2020-07-08