Airtightness Testing in Retrofit Housing
Airtightness testing in retrofit housing is important in meeting the UK’s net zero target by 2050. Retrofit is the process of making changes to an existing building to reduce its energy consumption and carbon footprint. With the implementation of government-funded schemes such as ECO, SHDF, LADs, HUGS, and ECO+, airtightness testing has emerged as a mandatory aspect of retrofit projects to ensure compliance with the PAS2035 standard.
Retrofitting involves upgrading the energy efficiency of a building by improving its insulation, airtightness, and ventilation. In some cases, conducting pre and post-air testing may be necessary to ensure compliance with PAS2035. Airtightness testing reveals areas for potential improvements. This can help save on costs associated with upgrading background ventilation, door undercuts, and mechanical extract systems.
What are the benefits of airtightness testing in retrofitted housing?
Airtightness testing in retrofit housing offers numerous benefits, enhancing energy efficiency and indoor comfort. Homeowners can significantly reduce energy consumption and lower utility bills by identifying and addressing air leaks. Improved airtightness enhances thermal comfort by maintaining consistent indoor temperatures and minimising drafts. Airtightness testing also helps to prevent moisture infiltration, reducing the risk of mould growth and structural damage. Properly sealed homes have better indoor air quality, as the controlled ventilation systems effectively manage pollutants and allergens. Ultimately, airtightness testing in retrofit housing contributes to a healthier, more comfortable living environment and promotes long-term sustainability.
Which methods are used in airtightness testing?
There are two main methods for airtightness testing in retrofit housing. These include the blower door test, typically used for new builds, and the pulse test, designed for retrofit projects.
1. Blower Door Test: This involves using a fan to depressurize the building and measuring the air flow rate required to maintain a constant pressure difference between the indoor and outdoor environments.
2. Pulse Test: This involves introducing a pulse of pressurized air into the building and measuring the resulting pressure decay over time to determine the building’s air leakage rate.
These tests can help assess a building’s airtightness and determine whether it meets the required standards. Air tightness testing not only measures air leakage but can also identify moisture risks associated with Risk Path A, B, and C. Risk Path A, B, and C are a classification system used to assess moisture risks in buildings. In relation to airtightness testing, Risk Path A involves defects in the building’s envelope, B involves internal moisture generation, and C involves the movement of moisture-laden air through the envelope. Moisture risks can cause significant damage to a building’s structure and affect indoor air quality. By identifying these risks early on, appropriate measures can be taken to manage and prevent moisture problems. In addition, good air tightness can help minimize the movement of moisture-laden air through the building envelope, reducing the risks associated with Risk Path C. Therefore, conducting air tightness testing can play a vital role in ensuring that the retrofitting process is done efficiently, effectively, and with minimal risk of moisture damage.
In compliance with PAS2035, airtightness testing for retrofit housing is required for projects classified as Path C, where the retrofit design includes any Energy Efficiency Measures (EEMs) for improving the building fabric and/or a ventilation upgrade. The Retrofit Installer must demonstrate compliance with the airtightness standard through approved testing. The PAS2035 ventilation assessment is an integral component of the whole-dwelling assessment.
In cases where the existing ventilation is deemed inadequate, it could be attributed to one or more of the following factors:
• Evidence of condensation and/or mould growth in the dwelling
• No ventilation system or the ventilation system is incomplete or not functional
• No undercut of at least 7000 mm2 beneath each internal door to allow air to move through the dwelling
• No provision for purge ventilation of each habitable room (e.g. by opening windows) as recommended by Building Regulations
An adequate, complete ventilation system includes the following:
• Intermittent extract ventilation (IEV) system consisting of fans in all wet rooms and background ventilators (to admit fresh external air) in all living spaces and bedrooms
• Passive stack ventilation (PSV) system consisting of passive stacks extracting air from all wet rooms and background ventilators (to admit fresh external air) in all living spaces and bedrooms
• Continuous positive input ventilation (PIV) system supplying fresh air and background ventilators (to allow moist, stale air to escape) in all other rooms
• Continuous mechanical extract ventilation (MEV) system that extracts moist stale air from all wet rooms combined with background ventilators to admit fresh external air to all living spaces and bedrooms
• Whole-house supply and extract mechanical ventilation with heat recovery (MVHR) system that continuously extracts moist stale from wet spaces and supplies fresh air to living spaces and bedrooms
PAS2035 requires upgrading the existing ventilation system to an appropriate system if it is deemed inadequate. This system must meet the ‘four Cs’ of safe retrofit housing: Control, Compartmentalisation, Contaminant Removal, and Comfort.
What’s the future of retrofitting and the need for airtightness testing?
Retrofitting existing buildings has become a priority with the push for more energy-efficient and sustainable living spaces. Airtightness testing ensures that retrofitted properties are adequately sealed and energy-efficient. As energy conservation gains emphasis in regulations and codes, demand for airtightness testing in retrofit projects will rise. Innovative technologies and improved testing methods will shape the future of retrofitting. These advancements will enhance our ability to create comfortable, energy-efficient living environments for years to come.
The Concluding Role of Airtightness Testing in Retrofit Housing
Airtightness testing is an indispensable component of retrofit housing projects. Retrofitting is becoming increasingly important as the UK aims to achieve ‘net zero’ by 2050. By adhering to the PAS2035 standard and utilising government-funded schemes, retrofit projects can ensure energy-efficient and sustainable homes for residents. Airtightness testing provides benefits like lower energy consumption, enhanced thermal comfort, improved air quality, and moisture infiltration prevention.
The primary methods used for airtightness testing in retrofit housing are the blower door test and pulse test. Compliance with PAS2035 is mandatory for projects classified as Path C. Airtightness testing can also be used on Risk Path A & B, which has the benefit of ensuring that the retrofitted house has the correct amount of ventilation, resulting in a further benefit of potential savings of time and money where no additional ventilation is required.
The focus on energy conservation and sustainable living spaces is growing, making airtightness testing increasingly vital in retrofit projects. Innovation and advanced testing will drive the future of retrofitting, fostering comfortable, energy-efficient homes for a greener future.
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