"Passive house" is the term given to a building in which a comfortable ambient temperature can be achieved without the use of a conventional heating system. This presupposes that the annual energy consumption will not exceed 15 kWh/m²a. The name derives from the fact that generally the sun's rays through the glass, coupled with the heat generated by the people and appliances within the building are sufficient to maintain a comfortable ambient temperature throughout the time that heating is required. The remaining heating requirement is supplied by warming the air current flowing through the existing ventilation system. Passivhaus guarantees a reduction of 80-90% in heating energy compared to traditional new-builds according to the German heat conservation mandate of 1995. This is also a given in that any Passivhaus design must be simulated in the PHPP (Passivhaus Planning Package) and meets the strict criteria of Passivhaus or not.

Windows for Passivhaus must demonstrate a Uw value of less than uW0.8 W/m²K where the glazing Ug = 0.7 W/m²K and a g-value of around 50 % . Internorm produces windows and doors for Passivhaus in both uPVC/Aluminium and Timber/Aluminium Clad. The KF410 is the Internorm level entry Passivhaus uPVC/Aluminium Clad window and matching door systems. The KF410 (uW 0.67) is actively specified on Passivhaus single, Multi Residential, Social Housing and schools, it is extremely cost effective and with Secured By Design and Life Time for Homes Compliance, it ticks all of the key “must have” attributes Architects will require. The KF410 is particularly successful for Main Contractors on Design Builds projects, cost effective and supported by a 30 Year Quality Assurance Warranty from Internorm.
The HF210 (uW 0.74) is the level entry Timber /Aluminium Clad system - available in home purehome soft and ambiente design. Again the HF210 has a matching door suite to include entrance, patio and sliding door options, all Passivhaus compliant in terms of uW value and Air Tightness. The HF310 (uW 0.69) is the Flagship Passivhaus Timber/Aluminium Clad composite window.
The most important factor in Passivhaus other than the obvious Passivhaus uW and Air Tightness performance is the need for absolute quality at the point of installation. EcoHaus Internorm insists on installing all windows and doors into Passivhaus projects. The reason is very simple, we must guarantee the integrity of the Air Tightness and the junction between the windows/doors and the building fabric. EcoHaus Internorm take this installation “artform” extremely seriously and also insist we have a Technician on site at the all critical Air Tests.

EcoHaus Internorm is the UK’s leading supply and installer into Passivhaus and Zero Carbon private and commercial projects. Our commitment to detail and ownership has resulted in a reputation based on quality at every level of every task we undertake. That, in Passivhaus, is an extremely rare occurrence.



Passivhaus is the single fastest growing energy performance standard in the world. The Passivhaus standards principle strengths are simple in theory, namely to construct a building that has incredible thermal performance, extraordinary airtightness with the aid of mechanical ventilation.

This simple and robust approach to construction design forces the designer to minimise the 'Heating Demand'. The heat generated internally is then recovered and circulated by a Mechanical Ventilation and Heat Recovery (MVHR) system.

The Passivhaus standard was developed in Germany in the early 1990s by Professors Bo Adamson of Sweden and Wolfgang Feist of Germany. The first dwelling to be completed to the Passivhaus Standard was constructed in Darmstadt in 1991. This first Passivhaus building is still subject to testing annually and some 24 years later still performs to Passivhaus. This data is regularly shared and discussed at the UK’s Passivhaus Conference proving the build standards longevity and sustainability. The Passivhaus standard is not restricted to residential dwellings but is actively used in commercial, multi-residential, schools, universities and public buildings.

The functional definition of a Passivhaus is -

“A Passivhaus is a building, for which thermal comfort can be achieved solely by post-heating or post-cooling of the fresh air mass, which is required to achieve sufficient indoor air quality conditions – without the need for additional recirculation of air.”

Essentially meaning the heating requirement in a Passivhaus is reduced to the point where a traditional heating system is no longer considered essential. Cooling is also minimised by the same principles and through the use of shading and in some cases via the pre-cooling of the supply air. Night purging and the use of natural cross-ventilation through open windows is encouraged during the summer months.

As well as being an energy performance standard Passivhaus also provides excellent indoor air quality and comfort, this is achieved by reducing the air infiltration rates and supplying fresh air which is filtered and post heated by the MVHR unit. The UK has the highest level of Asthma sufferers in Europe, largely down to our old and dilapidated building stock, PassivHaus would massively improve many Asthma related issues. Passivhaus is being actively considered for Elderly Care homes for air quality and comfort reasons alone.

The Passivhaus standard can be applied to any climate in the world and works equally as well in warm climates as it does in more moderate climates. 

The awareness and increased instances of fuel poverty increases the importance to reduce our dependence on fossil fuels. The continued and significant increases in fuel prices are “fuelling” the interest and momentum around Passivhaus as the single answer to our future construction direction. EcoHaus Internorm has supplied and fitted into prestigious single residential builds with total annual Energy bills of £60-£70. Many social housing units constructed to Passivhaus have total annual Energy bills of £32-£48 per annumeradicating fuel poverty for the tenants.


Are you planning a passivhaus project? To find out more on all of the Internorm range call us today on 0800 612 6519 or for more information use our contact form and we can get back to you with further information.

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