Evaluation of indoor pressure distributions in a detached house using the Pulse airtightness measurement technique

Building airtightness is a critical aspect for energy-efficient buildings as energy performance of a building can be reduced significantly by poor airtightness. The Pulse technique has been regarded as a promising technology, which measures the building airtightness at a low pressure of 4Pa by rapidly releasing a 1.5-second pulse of air from a pressurised vessel into the test building and thereby creating an instant pressure rise that quickly reaches a “quasi-steady” condition. However, questions have often been asked on the test viability due to the nature of the test. One of the frequently raised questions concerns uniformity of the pressure distribution across the internal space of the test building during the air pulse release. To provide insight into this, experimental work was conducted to measure the indoor pressure distribution during the pulse pressurisation process. The effect of the specific pulse release location on the building airtightness measurement has also been assessed by performing tests at various locations within the building. The test building, which is a five-bedroom house located in the University of Nottingham, was chosen for the testing. Five differential pressure transducers were used to obtain the pressure distribution within the dwelling. In addition, an ultrasonic anemometer was employed to measure the outdoor wind condition to eliminate the impact of wind on the indoor pressure. All the tests were conducted in December 2018 at wind speeds less than 0.5m/s (at a height of 2.2 metres above ground). The results show that a maximum relative percentage difference of 1.4% was obtained by comparing the pressure distribution between living room (Pulse test location) and the other rooms. This indicates that a pressure difference within the building during the Pulse test does exist but considering the accuracy of pressure transducers (0.15%), the deviation is not significant. Comparatively, smaller differences of the pressure level in the five rooms were observed in the fan pressurisation (Duct Blaster B, abbreviated as DBB) test at 10Pa and 15Pa, which are 0.5% and 0.2% respectively. In terms of building airtightness measurement, a subtle variation (i.e. 1.05%) is noted when the Pulse test was conducted at different locations on the ground floor, which may also be caused by variations in the environmental condition (e.g. temperature and wind condition).