The Design and Construction Process Implications of the Air-tightness Requirements of the Building Regulations Part L2 (original) (raw)

Air Tightness of New Australian Residential Buildings

Procedia Engineering

To achieve the energy efficiency standards in the National Construction Code, houses generally need to use insulation and weather sealing. However, if poorly installed this can lead to houses that have lower energy efficiency performance than expected. There has been little data collected on newly built houses to quantify airtightness and assess the quality of insulation. This paper reports on a study that investigated new house construction around Australia to gain insight into the quality of house construction with regard to air-tightness and quality of insulation. Twenty houses in each capital city, except Darwin, were recruited for the project. The houses in most cities were up to 3 years old and assumed to be at the 6 star NatHERS standard. Blower door testing was carried out on 125 of the volunteer homes and the resulting air changes per hour at 50 Pascals pressure (ACH@50Pa) for each house was then determined. In addition, an inspection of each house was undertaken by a qualified energy assessor to assess the quality of the insulation installed. A thermal inspection of the walls and ceiling was undertaken as well as a visual inspection of the ceiling insulation (if accessible). Weather sealing around windows and doors was also inspected for any gaps and damage. A broad range of results was achieved and found that well sealed houses are being constructed, but equally poorly performing houses are also still being built. To maximise value for energy in our houses, it is critical that we determine why these differences occur and how we can consistently build well sealed houses.

The effects and cost impact of poor airtightness - information for developers and clients

2007

Air movements in and through the building envelope affect the flows of not only heat, but also moisture, gases and particles, in a building. They often play a decisive part in determining moisture conditions, and thus indoor environmental conditions in the building, and ultimately, the durability of the building structure. Air flows affect thermal comfort and ventilation, and thus air quality. In addition, they also cause heat loss, both directly via ventilation, and through their effect on the performance of what are intended to be high-insulation structures. A previous joint project between SP Technical Research Institute of Sweden and Chalmers University of Technology investigated the importance of airtightness in the construction process. The project found that many types of damage and problems were caused by poor airtightness, that airtightness was seldom given the proper consideration that it deserved and that there was a major need for information on the effect of poor airtightness. One of the conclusions was that it is important to get developers/ clients to treat airtightness more seriously. The objective of the follow-on project that is described here is therefore to make developers/clients (more) aware of the potential damage that can be caused by poor airtightness, together with the "cost" of this damage/problem in a life-cycle perspective. Hopefully, developers/clients will then specify and monitor airtightness requirements more clearly. The aim is therefore to develop tools and methods for informing developers/clients of the importance of good airtightness, and of the resulting extra costs that incur from paying insufficient attention to airtightness. The project has identified and assessed various consequences of poor airtightness, such as increased energy use, reduced thermal comfort, reduced air quality and moisture damages. The cost calculations show that the developer/client would benefit in most cases from an increased standard and follow up on airtightness. We have projected the work with three different levels of ambition: 0.2, 0.4 and 0.6 l/m2s (at 50 Pa pressure difference), and believe that the optimal airtightness lies somewhere in the region of these values, depending on the buildings use and equipment.

DESIGN FOR AIRTIGHTNESS AND MOISTURE CONTROL IN NEW ZEALAND HOUSING

cmsl.co.nz

The analysis of the existing housing stock in New Zealand confirms the prevalence of indoor environmental factors negatively affecting occupant well-being. Besides being energy-consuming, New Zealand homes are known for having cold, damp and uncomfortable interiors. Furthermore, the country has one of the highest incidences of asthma and respiratory related illnesses in the developed world as well as one of the highest rates of winter related deaths.

Airtightness of Uk Dwellings: Some Recent Measurements Airtightness of Uk Dwellings: Some Recent Measurements

This paper reviews the results of some recent measurements of airtightness that have been undertaken on a small number of UK dwellings, which were identified as being potentially very airtight. The purpose of these measurements was to illustrate the levels of airtightness that can be achieved in practice in the UK if consideration is given to airtightness at both the design and construction stage, and identify the lessons that can be learnt from constructing and testing these dwellings. While the total number of houses involved in the work reported here is small, the results indicate that dwellings constructed with a wet plastered internal finish, can default to a reasonable standard of airtightness by UK standards (less than 7 m 3 /h.m 2 @ 50Pa) and that it is possible to build very airtight construction in the UK (around 4 m 3 /h.m 2 @ 50Pa), given a reasonable level of attention to design and construction. Nevertheless, the airtightness performance of these dwellings still falls short of best practice overseas.

Realising air leakage in Australian housing

Bedp Environment Design Guide, 2007

Air tightness of Australian buildings is a great unknown. Despite testing methods being developed and implemented in many advanced European and North American countries, this has not happened in Australia. This paper notes energy efficiency gains that can be achieved through tighter construction, and follows on from the investigation into testing methodology and literature discussed in TEC 23: Air Leakage in Buildings-Review of International Literature and Standards. Several domestic case studies are used to implement two accepted testing methods and aid to build the case for increased awareness of airtight housing in Australia.

Air leakage in buildings - review of international literature and standards

Bedp Environment Design Guide, 2007

This paper reviews the information available internationally on air leakage and testing of buildings, and reviews the systems and standards available. This paper and its companion paper TEC 24, originate from a Victorian study which gives an understanding of the issues and metrics of air leakage, and builds a case for further Australian research into air leakage of buildings.

The influence of construction and material solutions on the level of air tightness in single energy buildings

MATEC Web of Conferences, 2018

This publication focuses on the assessment of the impact of structural solutions of single-family buildings with an increased energy standard on their air-tightness level. The first part presents the threats resulting from the low tightness of the building. To formulate the conclusions, quantitative and qualitative casing tightness tests of existing single-family energy-efficient buildings were carried out. Construction and material solutions used in buildings were also analysed. The obtained results indicate that there is no impact of the building structure on its level of air tightness.

Airtightness Assessment of Single Family Houses in Belgium

International Journal of Ventilation, 2014

Airtight construction lies at the heart of achieving high energy performance in dwellings. But how well has is it applied in new construction? This paper presents results from airtightness measurements on 44 randomly selected, standard new built single family houses in Belgium and from 4 case studies including 78 additional measurements. The houses were randomly selected after completion, to assure that standard workmanship was used during construction. Where applicable, the effect of incorporating the attic and garage in the building volume was measured by performing a series of tests in different configurations. The results are compared with those from a previous study in the early 1990's, with a database that was compiled with results from 161 air tightness reports executed on newly built dwellings by private party consultants and with the governmental EPBDdatabase (1884 measurements). The results show that the mean leakage rate is about 6 ACH 50 for the randomly selected houses and 3 ACH 50 for the houses in the databases. The houses in the databases are measured upon the initiative of the owner. Therefore, the attention to airtight workmanship is substantially higher for these cases than in the randomly selected houses. This clearly demonstrates the difference between 'mainstream' workmanship and results obtained by the 'engaged' market.