Victoria Park House, Hackney, London
Passive House Design ////
In 2020 Material Works Architecture became certified Passive House Designers
What is Passive House ?
Passive House is a building standard developed in Germany in the 1990s that is being increasingly adopted as the gold standard for low energy building design. To achieve Passive House certification a building needs to meet a series of criteria demonstrating minimal energy consumption way below typical building practices. It is estimated that 28% of all global carbon emissions come from the running operation of buildings (heating, cooling and lighting). Passive house demonstrates a method whereby this can be reduced to zero, offering a powerful tool to tackle climate change.
The standard focuses on reducing heat-loss to such an extent that real advantage can be made of passive heat sources such as solar gain through glazing and the heat given off by a building’s occupants. This is measured through a series of calculations that take into account the thermal performance of the buildings materials, heating and ventilation systems, the location and orientation of the building and the expected passive thermal gains throughout the year.
#1 - Commercial viability
Passive house is often dismissed as difficult and costly, with much being made of the performance gap between typical construction methods and the standards required to meet Passive House. However, as the industry adapts to the realities of net zero ambitions and more stringent regulations come into this place, this gap is diminishing. Recent examples have shown passive house techniques can be applied as cost effectively as typical construction and become even cheaper when taking into account the reduced long term running costs. We believe forward thinking developers, professionals and contractors should adopt the standards now and we aim to incorporate passive house techniques into all ongoing projects.
#2 - Passive House Design
Early examples of Passive House design were restrained by the limited availability of high performance products and skills, often resulting in designs that met performance requirements but were not always attractive or imaginative architecturally. As manufacturing and design knowledge has advanced, and more designers have taken up the challenge, there is an increasingly varied and creative approach to Passive House architecture. Passive House design no longer prescribes a style or look but is simply a background approach that can be applied to any program or ambition. Similarly Passive House is no longer just about houses but has been successfully applied to schools, offices, hospitals and retail.
Agar Grove - Passive House Apartment block in London Hawkins Brown & Architype
#3 - Passive House Principals
The core principle of passive house design is to take a ‘fabric first’ approach - to focus the design on achieving a highly insulated and air-tight building envelope. With this in place, not only is energy consumption greatly reduced but a building can take real advantage of passive heat from solar gain as well as occupants and background gains. The five core principals of Passive House design are -
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Insulation - thick insulation is used around the entire envelope fo the building to reduce heat-loss through walls, roofs and foundations
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Thermal bridge reduction - all connection details and joints are designed to eliminate heat loss through thermal bridges
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Glazing - efficient triple glazed windows are used to reduce heat-loss and orientated to take advantage of solar gain
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Air-tightness - An Air tight layer is integral to the design to ensure there is negligible flow of cold from the outside. Buildings are pressure test prior to occupation to ensure air-tightness
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Ventilation - An active whole house system is used with a heat-recovery unit that uses warm extracted air to heat cold incoming air. The system provides filtered and warmed air throughout.
UAE Enterprise Centre - Passive House Design Office / Education building by Architype
#4 - Passive Performance Criteria
When applied correctly these techniques will a building to will achieve the passive house requirements
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Space heating demands of less than 15kwh per m2 per year as compared to averages of between 300 - 800 Kwh. Or alternatively maximum peak loads of 10w per m2
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Renewable Primary Energy Demand (total energy used by all heating and other appliances) of less than 06kwh per m2
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Airtightness of maximum 0.6 air changes per hour at 50 Pascal pressure
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Thermal comfort to maintain internal winter temperatures over 20°C and less than 10% of annual hours over 25°C
#5 - Embodied Carbon
Although 28% of the the world's carbon emissions stem from building operation, a further 11% is generated by the construction industry itself through the energy required to produce and transport materials. Currently Passive House standards focus only on operational emissions but clearly this needs to be adapted to also measure embodied carbon. A building with zero operating energy can hardly be seen as effective if its own construction involved significant emissions. Standards now need to be adapted to encourage materials and techniques with low embodied carbon. This is currently the topic of much debate within the industry and is likely to become incorporated into future standards.