Four mechanical ventilation heat recovery (MVHR) units from EnviroVent, one of the UK’s leading ventilation manufacturers, have been approved by the Passive House Institute, for use in Passive House developments.

EnviroVent’s energiSava® 300 and 400 and Slimline 150 and 300 units have been awarded a PHI Component Certificate, after each one passed rigorous quality and energy performance tests set by the Passive House Institute.

The Passive House Institute (PHI) is an independent research institute founded 1996 by Dr Wolfgang Feist with a continuously growing interdisciplinary team of employees. PHI has played an especially crucial role in the development of the Passive House concept. The first pilot project ( Kranichstein Passive House, Darmstadt, Germany, 1990) was Europe’s first inhabited multi-family house to achieve a documented heating energy consumption of below 10 kWh/(m²a), a consumption level confirmed through years of detailed monitoring.

The Passive House Institute is constantly developing and improving upon algorithms and software tools for dynamic building simulations, the determination of energy balances and the planning of Passive House buildings (for example, through the Passive House Planning Package). The Institute acts as an independent testing and certification centre for buildings and building components such as wall and construction systems, windows, doors, connections, ventilation systems and compact systems. PHI research staff also provide manufacturers of energy efficient components with in-depth consultancy on product development and optimisation. PHI further facilitates the upholding of the strict quality requirements set by the Passive House Standard through the professional certifications it offers worldwide.

Passive House and Ventilation

Ventilation units with heat recovery are key in terms of energy savings, as they ensure that the warmth carried by the exhaust air is not wasted, but first transferred to the incoming fresh air without the two air streams ever physically mixing. In extremely hot conditions, heat exchangers can also work in reverse so that the heat carried by the incoming air is transferred to the exhaust air and thus pre-cooled before entering the rooms. These systems should also be equipped with automatically controlled bypasses, thus allowing the incoming air to bypass heat exchange, for example, during the night at times when days are warm and nights are cool.

A Passive House can only function with a highly efficient heat recovery, as ventilation systems without heat recovery waste far more energy per year than a Passive House uses for heat (at the same rate of air exchange, a ventilation unit without heat recovery may lose about 24kWh/(m²yr) whereas a Passive House’s maximum space heating demand is only 15kWh/(m²yr).

The ventilation systems used in Passive Houses must thus have heat recovery efficiencies of at least 75% while the electricity consumption for such systems should not exceed 0.45 Wh/m³ of the transport air volume. Additionally, the acoustic load of the ventilation systems for use in Passive Houses should not exceed 25dB. Pipes and values should be planned accordingly, making use of silencers.

A ventilation system with heat recovery ensures that plentiful, nearly room temperature fresh air enters the building in a controlled manner. Draughts are eliminated and residents need not actively air out the rooms. It is important that the fresh air entering the building not exceed 30m³ per hour per person, so as to avoid overly dry air. Such a ventilation system should not be confused with air conditioning systems; humidifying the air within the ventilation system is to be avoided for reasons of hygiene.

The ventilation systems used in Passive Houses provide unparalleled indoor air quality through the use of a high quality, F7 filter at the suction point (the unit must also be equipped with a drain). During heat recovery, the exhaust air must not mix with the supply air. Due to reasons of hygiene, a humidifier within the ventilation unit is not possible. It is important to remember that Passive Houses utilise ventilation systems, NOT air necessarily conditioning systems.

The energiSava® models are high efficiency whole house heat recovery systems with maximum airflow capacities of 300 and 400 m3/h. The units are ideal for use within the home to provide a constant supply of clean air and reduce humidity levels, therefore preventing condensation and associated issues.

The Slimline 150 and 300 are high efficiency, compact mechanical ventilation heat recovery (MVHR) units with maximum airflow rates of 150 and 300 m3/h. With their low profile, compacted design, the systems are perfect for ceiling mounted applications and installation in smaller dwellings where space is restricted.

Rebecca McLean, Marketing & Product Director at EnviroVent, said: “Increasing numbers of self-builders are aiming to build to Passive House standards and this includes seeking ventilation solutions that meet PHI Certification. We are really pleased that a number of our units meet this standard, which demonstrates their energy efficiency and suitability for Passive House projects.”

The energiSava® and Slimline heat recovery systems work by extracting moisture laden air and re-supplying clean, fresh air into a property. The low energy consumption system creates an all-year-round, healthy indoor environment, which has been proven to help homeowners who suffer from asthma, hay fever and bronchial-related conditions.

Each unit features a summer bypass facility, which contributes to an improved comfort level during the season. This is controlled automatically by measuring indoor and outdoor temperatures.

The units also include innovative ‘constant flow’ technology which ensures that the commissioned airflow rate is always delivered. They also offer exceptionally low noise levels and are fully compliant with the ErP (Energy Related Products) Directive.

The energiSava® 300 and 400 units are easily operated via a simple 4-way switch, with filter indication, or a wireless remote control. Alternatively, the units can be set to work automatically using an intelligent control module with a timer, or a relative humidity sensor.

The Slimline 150 and 300 systems include a control module that can be used to adjust the basic settings and air flow rates. The built-in timer function can be used to set the ventilation rate per day, week or weekend. In addition, specifiers can opt for one or more 4-way switches, wireless RF controls or a humidity sensor.

EnviroVent, which has its headquarters in Harrogate, North Yorkshire, has over 30 years’ experience in delivering sustainable products to improve indoor air quality and reduce condensation and mould.

For more information visit www.envirovent.com or call 0345 27 27 807.

EnviroVent MVHR Systems Receive PassivHaus Certification