© Colin Usher practicing as MicroArchiTecture c 2022
MicroArchiTecture Colin Usher . Architect

How our Passive house works: page 1

19 Lang Lane: Probably the best house in the UK, as judged in 2014!

The house continues to perform to an extremely high standard: in 2020 we imported less energy from the grid than we generated from the sun. In 2021 it made a small energy profit, so that the cost of energy was £125 less than the income from the exported electricity. In the 2022 heatwave the internal temperature never rose above 24C and was usually 22 to 23C.You can still view the BBC coverage of the house and the award at the BBC/News web site.

The vision

This house has been designed to prove the case that it is possible to build a high performance home at a competitive cost; but it also shows that the owners do not have to significantly change their lifestyles in order to live in such a building. This house is flexible, comfortable, it has high quality design features and includes the spaces and volumes which many modern homes omit. Yet it is eminently affordable. The building does not look out of place in its suburban setting, but is bold and responds carefully to its site location. Internally the spaces feel generous without being excessive and the varied volumes of the rooms makes living there an enjoyable experience. It was also easy to build. There were no complex construction processes. Any small house builder could construct a house like this with very little extra skill being required. Attention to detail is needed, particularly in relation to the air tightness, but thin joint blockwork lends itself to this as a matter of course. This house is ground breaking by being simple and economical to build, comfortable to inhabit and by having low running costs and a tiny carbon footprint of just 11Kg/year. Yet no part of the aesthetics have been sacrificed to the functional brief

Insulation

The house is exceptionally well insulated to achieve a minimum U value of 0.1W/m2K. There are no traditional foundations, with the ground floor raft floating on 200mm of insulation. Windows and doors are triple glazed with a U value of between 0.7 and 1 W/m2K. The insulation on the walls wrap round in front of each of the window and door frames preventing thermal bridging.

Air Tightness

In modern well insulated homes the primary heat loss mechanism is through ventilation and air leakage through the fabric of the building and round the various construction discontinuities, such as window and door junctions with the walls. In this dwelling there are no draughts! The house is almost hermetically sealed. In winter a ventilation system has to be used. Air tightness tested to 1m3/(h.m2). Thin joint blockwork construction is a very air tight form of construction and, used in conjunction with external wall insulation, provides extremely robust results. No draught = comfort! In houses with draughty rooms the air temperature has to be much higher to offset the heat lost from the bodies of the people occupying the house. In this house that is never the case as the surface temperatures are always the safe and there is no discernable air movement. Draught Lobbies The house was designed to have a draught lobby at the front door and to use the unheated utility room to act as one at the rear. However this has proved to be almost unnecessary as the house is so well sealed. On a windy day one external door can be left open for some time without significant heat loss occurring because there is nowhere for the warm air within the house to be blown to – there is no exit route for the air. So only very localised cooling actually occurs.

Thermal Mass

The house is largely built of concrete to retain heat in winter and maintain a stable temperature in summer. This high thermal mass maintains a very stable internal thermal environment. Even in winter the building temperature only degrades by about 1 degree per day when the heating is switched off. Ground floor: 200mm cast concrete with 100mm sand cement screed. First floor: 200mm cast concrete with power floated finish. Direct plaster finish to underside. External walls: 150mm thin joint light weight concrete blocks. Direct plaster finish to inside. Internal walls and partitions: 100mm dense concrete blocks. Direct plaster finish to both sides.

Volume

Natural cooling by volume and mass: South facing ground floor rooms have 3m ceiling heights to ensure stratification of air allowing the warm air to rise to the ceiling and transfer heat into the concrete first floor, resulting in those rooms never rising above 23C in the summer of 2014. The central stair void rises 8.6m from the ground floor and acts as a chimney to remove hot air in summer. The 2 roof windows at the apex can be opened remotely to allow the escape of warm air. The additional height in these rooms also results in the window heads being higher than normal for a modern house. As the daylight factor is significantly increased with higher window height this has the added benefit of improving the natural daylighting in the living room and studio.
© Colin Usher practicing as MicroArchiTecture c 2022
MicroArchiTecture Colin Usher . Architect

How our Passive house works: page 1

19 Lang Lane: Probably the best house in the

UK, as judged in 2014!

The house continues to perform to an extremely high standard: in 2020 we imported less energy from the grid than we generated from the sun. In 2021 it made a small energy profit, so that the cost of energy was £125 less than the income from the exported electricity. In the 2022 heatwave the internal temperature never rose above 24C and was usually 22 to 23C.You can still view the BBC coverage of the house and the award at the BBC/News web site.

The vision

This house has been designed to prove the case that it is possible to build a high performance home at a competitive cost; but it also shows that the owners do not have to significantly change their lifestyles in order to live in such a building. This house is flexible, comfortable, it has high quality design features and includes the spaces and volumes which many modern homes omit. Yet it is eminently affordable. The building does not look out of place in its suburban setting, but is bold and responds carefully to its site location. Internally the spaces feel generous without being excessive and the varied volumes of the rooms makes living there an enjoyable experience. It was also easy to build. There were no complex construction processes. Any small house builder could construct a house like this with very little extra skill being required. Attention to detail is needed, particularly in relation to the air tightness, but thin joint blockwork lends itself to this as a matter of course. This house is ground breaking by being simple and economical to build, comfortable to inhabit and by having low running costs and a tiny carbon footprint of just 11Kg/year. Yet no part of the aesthetics have been sacrificed to the functional brief

Insulation

The house is exceptionally well insulated to achieve a minimum U value of 0.1W/m2K. There are no traditional foundations, with the ground floor raft floating on 200mm of insulation. Windows and doors are triple glazed with a U value of between 0.7 and 1 W/m2K. The insulation on the walls wrap round in front of each of the window and door frames preventing thermal bridging.

Air Tightness

In modern well insulated homes the primary heat loss mechanism is through ventilation and air leakage through the fabric of the building and round the various construction discontinuities, such as window and door junctions with the walls. In this dwelling there are no draughts! The house is almost hermetically sealed. In winter a ventilation system has to be used. Air tightness tested to 1m3/(h.m2). Thin joint blockwork construction is a very air tight form of construction and, used in conjunction with external wall insulation, provides extremely robust results. No draught = comfort! In houses with draughty rooms the air temperature has to be much higher to offset the heat lost from the bodies of the people occupying the house. In this house that is never the case as the surface temperatures are always the safe and there is no discernable air movement. Draught Lobbies The house was designed to have a draught lobby at the front door and to use the unheated utility room to act as one at the rear. However this has proved to be almost unnecessary as the house is so well sealed. On a windy day one external door can be left open for some time without significant heat loss occurring because there is nowhere for the warm air within the house to be blown to – there is no exit route for the air. So only very localised cooling actually occurs.

Thermal Mass

The house is largely built of concrete to retain heat in winter and maintain a stable temperature in summer. This high thermal mass maintains a very stable internal thermal environment. Even in winter the building temperature only degrades by about 1 degree per day when the heating is switched off. Ground floor: 200mm cast concrete with 100mm sand cement screed. First floor: 200mm cast concrete with power floated finish. Direct plaster finish to underside. External walls: 150mm thin joint light weight concrete blocks. Direct plaster finish to inside. Internal walls and partitions: 100mm dense concrete blocks. Direct plaster finish to both sides.

Volume

Natural cooling by volume and mass: South facing ground floor rooms have 3m ceiling heights to ensure stratification of air allowing the warm air to rise to the ceiling and transfer heat into the concrete first floor, resulting in those rooms never rising above 23C in the summer of 2014. The central stair void rises 8.6m from the ground floor and acts as a chimney to remove hot air in summer. The 2 roof windows at the apex can be opened remotely to allow the escape of warm air. The additional height in these rooms also results in the window heads being higher than normal for a modern house. As the daylight factor is significantly increased with higher window height this has the added benefit of improving the natural daylighting in the living room and studio.