In 2020 Material Works Architecture became certified Passive House Designers. 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 far below typical building practices. 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 building's materials, heating and ventilation systems, the location and orientation of the building and the expected passive thermal gains throughout the year.

 

In 2022, the mean average energy efficiency of properties in England was 66.5% and 48% had an EPC rating of C or higher. This means 52% of the existing building stock are highly inefficient and should be upgraded to reduce wasted energy spent through heating and cooling homes. 

 

It is estimated that 27% of all global carbon emissions come from the running operation of buildings (heating, cooling and lighting). Passive house is a method whereby this can be reduced to zero, offering a powerful tool to tackle climate change.

 

#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. We aim to incorporate passive house techniques into all ongoing projects.

 

#2 - 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. However more recently there is an increasingly varied and creative approach to Passive House architecture. Passive House design is simply a background approach that can be applied to any program or ambition.

 

#3 - Principles

 

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 principles of Passive House design are:

 

Insulation - thick insulation is used around the entire envelope of the building to reduce heat-loss

 

Thermal bridge reduction - all connection details and joints are designed to eliminate heat loss

 

Glazing - efficient triple glazed windows are used to reduce heat-loss and orientated to take advantage of solar gain

 

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 tested prior to occupation to ensure air-tightness

 

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.

 

#4 - Performance Criteria

 

When applied correctly these techniques within a building will achieve passive house standards:

 

- 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

 

- Renewable Primary Energy Demand (total energy used by all heating and other appliances) of less than 6kwh per m2

 

- Airtightness of maximum 0.6 air changes per hour at 50 Pascal pressure

 

- Thermal comfort to maintain internal winter temperatures over 20°C and less than 10% of annual hours over 25°C