The certification of Passivhaus buildings is subject to rigorous quality control. In realising you certified Passivhaus project it will be necessary to carry out testing during construction and once the house is complete and fully commission the building services, in particular the MVHR system.
Ensuring that your project meets the design air tightness standard will require an air tightness test (also known as a blower door test) upon completion, however we would advise at least one additional test earlier in the build – once the air tight layer is complete. This will allow early identification and rectification of any problems, saving on costs in the long run. BRE is able to carry out air tightness testing for your project.
Commissioning of the ventilation system is important, as it is critical to the successful operation of Passivhaus buildings. On site checking will involve making sure that the system is balanced, acoustic performance is in accordance with PHI guidelines, insulation is correctly applied to ductwork, appropriate filters are properly installed and frost protection thermostats are correctly set.
Whilst not a certification requirement, a thermographic survey may be useful to ensure continuity of insulation used in the building fabric, correct implementation of thermal bridge free detailing and on service installations such as hot water pipes and ventilation ducts.
Ongoing building performance monitoring of may involve placing environmental sensors throughout, as well as monitoring the external environment and fuel consumption. Analysis of the data collected from these sensors can then be used in order to build up an accurate picture of how a building behaves in different conditions.
See below for a list of BRE's standard testing.
Backed by an extraordinary range of facilities our experts are able to test both on and off-site and test individual materials and products, building systems, engineering structures and whole buildings, using both well established methods and bespoke research tests and simulations. We typically test against published standards, but can develop dedicated procedures for new, unique or innovative products.
BRE is able to carry out the co-heating testing which is a method of measuring the heat loss (both fabric and background ventilation) in W/K attributable to an unoccupied building to an elevated mean internal temperature (typically 25 °C) over a specified period of time, typically between 1 to 3 weeks. By measuring the amount of electrical energy required to maintain the mean internal temperature, the heat input to the building can then be determined.
The heat loss coefficient for the building is calculated by plotting the heat input against the difference in temperature between the inside and outside of the building (ΔT), resulting in the heat loss coefficient in W/K.
In order to obtain a sufficient value of ΔT the co-heating test should be carried out in the winter months, usually between October/November and March/April.
Infrared Thermographic Study
Where possible (weather conditions allowing), thermal imaging will be carried out on each dwelling during the heating season (after an appropriate period of heating of the dwelling) both externally and internally using an infrared camera – in order to show fabric heat losses and to show heat-loss paths.
Measurement of Whole-house Ventilation Rate
Whole-house ventilation rate can be measured for each dwelling using a tracer gas (butane) decay technique. A whole-house ventilation rate of between 0.5 and 1.0 ach (air changes per hour) is considered to be normally sufficient to control the build up of moisture. This will normally prevent humidity levels exceeding 70% for prolonged periods and so mitigate the associated consequent risk of condensation on surfaces and mould growth.
Spot Measurements of Temperature, RH, CO and CO2
Measurements of temperature, relative humidity (RH), CO (carbon monoxide) and CO2 (carbon dioxide) can be measured at various location within the dwelling using a QTrak monitor. CO is a colourless, odourless gas, produced by the incomplete combustion of most fuels. CO2 is a colourless, odourless gas, and a bio-effluent, whose concentration is a good indicator for efficacy of ventilation.
Measurement of VOCs
Volatile Organic Compound (VOC) concentrations can be measured at various location within the dwelling by pumped sorbent tube sampling and TD-GC-MS analysis according to ISO 16000-6 (Indoor air – Part 6: Determination of volatile organic compounds in indoor and test chamber air by active sampling on Tenax TA sorbent, thermal desorption and gas chromatography using MS/FID). VOCs are emitted over periods of weeks or years from construction and furnishing products and have the potential to cause poor air quality. There is a growing interest in release of VOCs from consumer products including electrical goods such as computers and printers as well as cleaning products and air fresheners. Environmental tobacco smoke (ETS) contains a complex mixture of organic compounds and while smoking is banned in the workplace and public buildings in the UK, it remains a significant source of airborne pollution in many homes.
Measurement of Formaldehyde
Formaldehyde concentrations can be measured in building by pumped cartridge sampling and HPLC analysis according to ISO 16000-3 (Indoor air – part 3: Determination of formaldehyde and other carbonyl compounds – active sampling method). Formaldehyde is a very volatile organic compound (VVOC) that has been widely studied with regard to indoor air because of its release from a range of building and consumer products.
Continuous Monitoring of Temperature and Relative Humidity (RH)
This can be undertaken for a period of 12 months post occupancy by mounting battery-operated Tiny Tag data loggers in various rooms within each building (and typically one weather-resistant logger outside the dwelling). The frequency of temperature and RH readings can be chosen to suit frequency of data download.
More information on BRE Testing and Monitoring can be found here.