airtightness

A new low pressure ‘quasi-steady’ pulse technique for determining the airtightness of buildings has been developed further and compared with the standard blower-door technique for field-testing a range of typical UK homes. The reported low pressure air pulse unit (APU) has gone through several development stages related to optimizing the algorithm, pressure reference and system construction. The technique, which is compact, portable and easy to use, has been tested alongside the standard blower-door technique to measure the airtightness of a range of typical UK home types.

Since 2006, the French Energy Performance regulation, named RT, has been allowing two ways to justify building airtightness: either with a measurement or with the application of a quality management approach. The quality management approach certification is managed by the French Ministry in charge of construction, for which it set up a specific expert committee to assess quality management approaches. Since 2012, the justification has been compulsory for residential buildings. This obligation led to a more systematic use of certified quality management approaches.

Mastering building airtightness is essential to meet the requirements of current and future building codes, not only for saving energy but also for ensuring moisture safety. Perfect airtightness is difficult to achieve: failures are often observed, due to bad design or poor workmanship. Some published investigations proved that leaking air mostly flows through porous material and thin air channels, due to material imperfections and construction tolerances.

In 2014 the first multi storey residential building planned and constructed to meet the Passivhaus Institute (Darmstadt) criteria was put in operation in Ljubljana, the capital of Slovenia. This massive-structure building is part of the FP7 EE-Highrise project, aiming to demonstrate nearly zero energy building (nZEB) technologies, an integrated design concept, and advanced systems for sustainable construction.

Old buildings that represent and maintain historic values often have poor indoor conditions and energy efficiency. The aim of this work was to evaluate the influence of building structures on airtightness and energy performance of certain historic building types. In this study on-site measurements, dynamic simulation and questionnaires were used. Significant differences between the levels of the airtightness of the historic houses exist in the studied region. No statistically significant correlation was found between the structure types and the envelope tightness.

We have analysed the steady wind model error based on a simplified building model with one leak on the windward side and one on the leeward side of the building. Our model gives an analytical expression of this error that depends on the leakage distribution and pressure coefficients. Using a test pressure of 50 Pa in this model, standard measurement protocol constraints contain the steady wind model error within about 3% and 11% with wind speeds below 6 m s-1 and 10 m s-1, respectively. At 10 Pa, the error is in the range of 35% and 60% at 6 m s-1 and 10 m s-1, respectively.

The characterization of power-law coefficients of the airflow through ventilation system components and ductwork or building leaks should include corrections on the airflow rate measurement because of two phenomena: a) the temperature and pressure conditions at the flow measurement device may not be the same as those seen by the test object; b) the temperature and pressure conditions experienced by the object may differ from reference conditions. This paper gives the analytical expression of these corrections depending on the air viscosity, air density and flow exponent.

The article presents the results of our research, which was realized under a cooperation project between the University of Pécs, Hungary and the University of Osijek, Croatia. The aim was to gather 50 Pa ACH, air tightness and spontaneous ACH information of residential houses by the Croatian and Hungarian border. The budget of the project allowed approximately 50 tests for each university; these summarized results are presented together with correlations found between the results.  

In Sweden, the energy usage in existing residential buildings amounted to 147 TWh in 2012, equivalent to almost 40 % of the final overall national energy usage. Among all the end users in building service sectors, 60 % of the final energy in Sweden is used for space heating and domestic hot water (DHW) production in 2013.

During field measurements on the airtightness of passive houses, ventilations system’s roof penetrations showed to be one of the major leakage paths, as they were not sealed using the appropriate, durable techniques. Therefore, a series of laboratory measurements was conducted on wood-frame walls to study different air sealing solutions. The use of special airtight gaskets is compared to less advanced sealing methods such as sprayed polyurethane foam and the use of pieces of tape.