The effectiveness of mechanical exhaust ventilation in dwellings

Ventilation systems play an important role in providing a good indoor air quality in dwellings. Mechanical exhaust ventilation systems implement natural vents to supply outdoor air to the dwelling. Natural driving forces, i.e. wind and thermal draught, influence the flow rates through these supply vents. Therefore, the flow rates depend on the weather conditions and vary in time. This study considers the influence of the wind and thermal draught on the operation of a mechanical exhaust ventilation system in a reference dwelling.

Component leakage: potential improvement graphs and classification of airpaths

Last years, interest in airtightness increases among all construction fields and airtightness becomes a major issue in the reduction of energy consumption in buildings. Nevertheless, there is a lack of understanding of air displacements through weak spots in buildings (airpaths). Firstly we develop first the concept of Potential Improvement Graph (PIG chart). These graphs represent the “improvement curves” of a given airpath (airflow indicator against airpath parameter). As an airpath can have multiple significant parameters, PIG charts can be n-dimension graphs.

Long-time durability of passive house building airtightness

An airtight building envelope ensures not only the energy-efficiency of a building, but also a damage free construction. Important to achieve optimal airtightness are the planning, implementation and materials. Long-term airtightness requires efforts in all three aspects. Airtightness products are being tested under lab conditions but these results cannot be transferred one-on-one onto buildings.

Assessment of the durability of the airtightness of building elements via laboratory tests

The airtightness just after the end of a building phase is assumed to be relevant criteria for high energy performance. Testing on site the initial performance of the airtightness via the blower door test has become nowadays a common practice but generally implemented before the occupation of the building. But a lot of questions are still remaining targeting the sustainability of the performances.

Statistics, analysis and conclusions from 250,000 blower door tests, including ventilation types

With lower air leakage in modern homes, ventilation of homes has become more important than ever before. It seems however that we are getting it very wrong. A lack of ventilation can cause building sickness, with degradation of the physical building and also poor air quality which has a big impact on the occupants themselves. Our statistics show that designers and contractors are still not getting it right, leaving us with a generation of poorly ventilated housing stock.

Influence of air quality performance requirements on the demand of energy

The aim of this paper is to show the effects of variable ventilation rates on the demand of energy and air quality in dwellings, and how airtightness and wind affect this relation. It is interesting to estimate the relation between the air ventilation rate and airtightness of dwellings which makes the dwelling to be under-pressure in order to avoid infiltrations.

Optimization of the airtightness and the flow rate of air in nearly zero energy buildings

The control of heat losses, inwards/out, in nearly zero energy buildings is of high importance. The transmission losses through the building envelope are easily reduced using larger amounts of insulation. Calculation of the impact of this action on the total energy demand of the building, is quite standard. It’s however much more difficult to determine the efficiency of actions to increase the airtightness of the building and the influence of the ventilation system.

Numerical evaluation of the airtightness impact on airflow pattern in mechanically ventilated dwellings in France

The objective of this paper is to assess the impact of the envelope airtightness on airflow patterns for single detached dwellings depending on the ventilation system.

Infiltration and Ventilation in a Very Tight, High Performance Home

The Net Zero Energy Residential Test Facility (NZERTF) was constructed at the National Institute of Standards and Technology (NIST) to support the development and adoption of cost-effective net zero energy designs and technologies. Key design objectives included providing occupant health and comfort through adequate ventilation and reduced indoor contaminant sources.

Laboratory investigation on the durability of taped joints in exterior air barrier applications

In timber frame construction in Europe air barrier systems are typically realised at the interior side of the building envelope. Yet in some applications such as renovation projects it can be easier to provide the air barrier layer at the exterior. This way, the air barrier system – typically board materials in which the joints are sealed with tape – is exposed to outdoor weather conditions. The aim of the present article is to investigate the impact severe climatic conditions on the airtightness of typical taped joints.