7 low-energy ModCell homes

These 7 terraced homes located in Shirehamton, Bristol, UK, constitute the world’s first commercially available straw eco-homes, using the BM Trada Q Mark certified ModCell Core prefabricated straw bale panel system. As part of the planning requirement the panels are clad with the traditional red brick, that complements the look and feel of existing neighbouring Shirehampton homes. This handsome row of housing comprises five 3 and 4 bedroom homes, and two 2 bedrooms homes that bookend the development. Each house has full height timber fences as well a shed to store bikes and other household goods.

Behind the traditional brick elevation of the St Bernard’s Road development is a state of the art, super insulated, low carbon straw bale construction system by ModCell: the recently BM Trada Q Mark certified ModCell Core prefabricated straw bale panel system. The excellent insulating properties of straw encapsulated in the walls of the project can reduce heating bills by up to 90% compared to the average for Bristol.

All internal wall partitions are made from Coobio Compressed Straw Board panels (CSB), replacing conventional plasterboard which has a negative environmental impact, and providing instead a fully carbon negative build system with excellent acoustic insulation between rooms.

The rear garden has been turfed and has a timber deck as standard. Some of the units have chosen to have oak flooring fitted in the open plan ground floor.

Progetic designed the Mechanical Ventilation with Heat Recovery (MVHR) systems for the homes, which cleverly swap heat from the outgoing air into the incoming fresh air, ensuring stable temperatures, better air quality and drastically reduced heating bills and carbon footprint. The combination of straw bale construction and MVHR means the homes stay warm in winter, cool in summer and are healthy and comfortable to live in.

Heating is provided by a high efficiency air source heat pump that extracts heat from outdoor air and transfers it to water, which is circulated through low temperature radiators around the homes. The same system provides domestic hot water generation.

Additionally,each home is fitted with a 2.2 kWp grid-tied solar PV array. The green electricity they generate can be instantly self-consumed and/or exported to the grid, receiving a feed in tariff that reduces occupants’ electricity bills.

All homes come with 'A+ or A++' appliances and broad spectrum LED lighting.

Each home is equipped with a rain water harvesting system. The Washing machine,toilets and garden will all draw their water needs from the rain water harvesting tank.

See more details about this project

http://www.st-bernards-portway.co.uk/
http://www.modcell.com/projects/straw-eco-homes-nearly-finished/

Data reliability

Self-declared

Stakeholders

Function : Thermal consultancy agency

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Function : Designer

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Function : Developer

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Function : Contractor

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Function : Manufacturer

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Function : Manufacturer

Owner approach of sustainability

The 7 terraced homes that make up this development constitute the world's first commercially available straw Eco-homes, using the recently BM Trada Q Mark certified ModCell Core prefabricated straw bale panel system. As part of the planning requirement the panels are being clad with red brick.

Architectural description

The traditional red brick and tiled roof of St Bernard's Road complements the look and feel of existing neighbouring Shirehampton homes. This handsome row of housing comprises 5 three-storey properties with a room in the roof layouts, and two hipped-roof two-storey properties that bookend the development.
Behind the traditional brick elevation of the St Bernard's Road development is a state of the art, super insulated, low carbon straw bale construction system by ModCell: the recently BM Trada Q Mark certified ModCell Core prefabricated straw bale panel system. The excellent insulating properties of straw encapsulated in the walls of the project can reduce your heating and cooling bills by up to 90% compared to the average for Bristol.
All internal wall partitions are made from Compressed Straw Board panels (CSB), providing a fully carbon negative build system with excellent acoustic insulation between rooms.

If you had to do it again?

The house is warm and the MVHR system is quiet. Very comfortable

Energy consumption

Primary energy need : 120,00 kWhpe/m².year
Primary energy need for standard building : 200,00 kWhpe/m².year

Calculation method :

CEEB : 0.0001

Final Energy : 46,20 kWhfe/m².year

Breakdown for energy consumption :

- Space Heating: 10.2 kWh/(m2a)
- Hot Tap Water [DHW]: 10.3kWh/(m2a)
- Electricity: 25.9 kWh/(m2a)

Envelope performance

Envelope U-Value : 0,13 W.m^-2.K^-1

More information :

Behind the traditional brick elevation of the St Bernard’s Road development is a state of the art, super insulated, low carbon straw bale construction system by ModCell: the recently BM Trada Q Mark certified ModCell Core prefabricated straw bale panel system. The excellent insulating properties of straw encapsulated in the walls of the project can reduce heating bills by up to 90% compared to the average for Bristol.
All internal wall partitions are made from Compressed Straw Board panels (CSB), replacing conventional plasterboard which has a negative environmental impact, and providing instead a fully carbon negative build system with excellent acoustic insulation between rooms.

Building Compactness Coefficient : 0,61

Indicator : EN 13829 - q50 » (en m3/h.m3)

Air Tightness Value : 3,00

Systems

Heating system :

Heat pump

Hot water system :

Heat pump

Cooling system :

No cooling system

Ventilation system :

Natural ventilation
Double flow heat exchanger

Renewable systems :

Solar photovoltaic

Renewable energy production : 29,00 %

Progetic designed the Mechanical Ventilation with Heat Recovery (MVHR) systems for the homes, which cleverly swap heat from the outgoing air into the incoming fresh air, ensuring stable temperatures, better air quality and drastically reduced heating bills and carbon footprint. The combination of straw bale construction and MVHR means the homes stay warm in winter, cool in summer and are healthy and comfortable to live in.
Heating is provided by a high efficiency air source heat pump that extracts heat from outdoor air and transfers it to water, which is circulated through low temperature radiators around the homes. The same system provides domestic hot water generation.

All homes come with 'A+ or A++' appliances and broad spectrum LED lighting
Finally, each home is equipped with a rain water harvesting system. The Washing machine, toilets and garden will all draw their water needs from the rainwater harvesting tank.

Each home is fitted with a 2.2 kWp grid-tied solar PV array. The green electricity they generate can be instantly self-consumed and/or exported to the grid, receiving a feed in tariff that reduces occupants’ electricity bills.

Solutions enhancing nature free gains :

Heat Recovery System

GHG emissions

GHG in use : 31,00 KgCO₂/m²/year

Methodology used :

PHPP with GEMIS CO2 emissions data

Building lifetime : 100,00 year(s)

Indoor Air quality

Good indoor air quality is achieved by two means: firstly, indoor air is continually replenished with full fresh, filtered, and pre-heated outdoor air, via the mechanical ventilation with heat recovery system; secondly, almost all materials in contact with indoor air are bio-based, non-toxic and low VOC’s, meaning off-gassing is minimal and indoor contaminant generation is small.

Health & Comfort

Health & comfort : Thermal comfort is provided through high levels of thermal insulation, reduced thermal bridges, and minimal air leakage, meaning cold spots and draughts are kept to a minimum.

Product

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Product category : Génie climatique, électricité / Ventilation, rafraîchissement

PHI Certified heat recovery ventilation unit with heat recovery efficiency of 87%
For ventilation requirement of up to 150 m3/h

System is quiet and efficient, providing good air quality

Product category : Génie climatique, électricité / Chauffage, eau chaude

Electrical Input: 1.41 kW
Heating COP: 4.26 *Ambient air temperature 7°C and leaving water temperature 35°C (A7 W35)

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Product category : Second œuvre / Cloisons, isolation

ModCell® Core panels are 427mm deep, factory finished fully closed, dry lined panel system using breathable sheathing boards in place of the render. The standard internal finish is a sheathing board, battened (not included in above dimension) ready to recieve a variety of internal surface finishes, external finish is a breathable sheathing board, battened ready to receive a variety of rainscreen options.

U-Value: 0.13 W/(m2K)

Modular prefabricated system which is quick and easy to install.

Product category : Second œuvre / Equipements électriques (courants forts/faibles)

Array of 8 PV Modules with a total output of 1.96kWp

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Energy bill

Forecasted energy bill/year : 890,00 €

Real energy cost/m2 : 1.33

Real energy cost/Dwelling : 127.14

Urban environment

Informally known to locals as “Shire”, Shirehampton is a neighbourhood of some 7000 inhabitants, located near Avonmouth at the north-western edge of the city of Bristol, England. Originally a separate village, the area retains a village feel, with good access to all parts of the city and its work environment.

Land plot area

Land plot area : 363,00 m²

Built-up area

Built-up area : 160,00 %

Building Environmental Quality

indoor air quality and health
consultation - cooperation
comfort (visual, olfactive, thermal)
water management
energy efficiency
renewable energies
building process
products and materials

Reasons for participating in the competition(s)

The Low Carbon category has been chosen due to the fact that this development takes a holistic approach to carbon reduction in the built environment: embodied carbon in the building materials is drastically reduced through the use of timber and straw for structure and insulation, while operational energy use is reduced through high levels of thermal insulation, triple glazed windows, reduced air infiltration and efficient Passivhaus certified mechanical ventilation units with heat recover and automatic summer bypass.