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News Release from: PRP Architects | Subject: PRP challenge assumptions of carbon neutrality
Edited by the Buildingtalk Editorial
Team on 24 September 2007
PRP challenge assumptions of carbon
neutrality
Architects challenge assumptions of carbon neutrality as new concepts are unveiled in carbon challenge design competition.
A competition created to explore the issues arising from the introduction of the Code for Sustainable Homes has revealed new concepts and ideas that challenge assumptions of carbon neutrality The competition, Carbon Challenge 2007 - the second in a series of annual design competitions held at PRP to respond to industry issues - shows new approaches by PRP's architects that include embodied energy and solar gain, currently not part of the calculation of carbon neutrality
This article was originally published on Buildingtalk on 1 Dec 2005 at 8.00am (UK)
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Many of the schemes also acknowledge the importance of generating renewable energy for a wide area rather than relying on micro-generation, an implication of Code level 6* and much current planning policy.
PRP director, Andy von Bradsky, said: "Our competition has come at a timely moment in the architecture of housing.
All new homes in England are to be carbon neutral by 2016.
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Now that the challenge of zero carbon homes has reached the mainstream housing marketing, bearing in mind that the sector is notoriously conservative in terms of the homes they offer, we set out to explore whether low or zero carbon homes had to look different, and if accepted principles of good urban design, like place making, safety, legibility and privacy, had to change.
We wanted to see how our architects would respond to the challenge, what technologies they would embrace, what the architectural language might be and how the site would be laid out".
A total of 8 entries were submitted from across PRP's multidisciplinary practice.
Interestingly, a number of common themes emerged alongside some unique concepts, including:.
- Consideration of the wide area context in terms of energy generation and supply through new infrastructure.
- Wind turbines and CHP fuelled by bio-gas or bio-mass sourced locally.
- Need for flood defence and storm water storage combined with grey water recycling on a site-wide basis.
- A neighbourhood approach to issues to car pooling, community facilities and workspace to address social and economic sustainability as well as environmental sustainability.
- Incorporating devices and methods that encouraged a change in lifestyle of the occupants - such as real time data systems.
- Incorporating live/work accommodation to reduce car usage, the single biggest contributor to people's carbon footprint.
- Sourcing local food or facilitating farmers' markets for locally grown food and orchards within the developments.
- Linkage with farms for bio-gas production.
- Adaptive house principles for future flexibility.
- Use of heat pumps, solar heating, photovoltaics and wind turbines on house types as a supplement to the area wide renewable energy generation.
- Use of natural materials such as rammed earth and timber frame Trombe walls for heat storage and transfer.
- Passivhaus principles for the building fabric to minimise heat loss.
- Passive stack ventilation from earth tubes for warmth in winter and coolth in summer.
- Use of geothermal energy.
- Use of new emerging technologies such as sun tubes, monitoring devices and electrical offsetting devices.
von Bradsky added, "Clearly a challenge ahead will be how architects can incorporate the requirements to design homes and keep them affordable.
Homes do not need to look radically different, however, there is opportunity to develop an aesthetic based on the functional needs of zero carbon housing.
Long term flexibility, through adaptable and extendable plans, fascinates us as architects but we also face challenges such as summer overheating and adequate space for recycling bins and cycle storage".
We set a target for a part of a typical greenfield urban extension to achieve Code Level 6* and the site and brief was modelled on the requirements of English Partnership's Carbon Challenge competition for a carbon neutral development on a series of sites nationwide.
The site was a modest 30-40 unit scheme, part of a wider masterplan for Kings Reach, Biggleswade, set to a density not exceeding 40-50 dwellings per hectare.
Paul Willis, Head of Construction, at Places for People, and David Taylor of Alan Baxter and Associates, supported PRP directors in the judging of entries.
Paul Willis, said, ""The whole of the construction industry is grappling with the challenge of building low or zero carbon developments.
I was particularly impressed with the very high levels of enthusiasm and energy that PRP displayed by organising internal design competitions to address such a key issue.
I hope that the approach, quality and standards demonstrated by PRP's architectural teams are reflected in other practices in the industry, in which case organisations like Places for People, who aim to create sustainable developments where people choose to live, should be truly encouraged".
The Carbon Challenge booklet, featuring all eight design concepts, can be downloaded from the website, or to obtain a copy of the design booklet, please contact Vanessa Clarke (vanessa.clarke@prparchitects.co.uk).
Winner - Home is Where the Heart Is.
This design addresses the issues of sustainability at a number of levels - from a wide area Heart of the Community, Heart of the Neighbourhood Block, and Heart of the House - with strategies applied at each level.
The wide area renewable energy strategy provides wind generation and bio-mass combined heat and power (CHP) for the whole of the urban extension, food supply from local farms and bio-mass production from local forests.
At a neighbourhood level, community allotments and a community hub on the site is incorporated to serve a number of blocks with a cafe, gym, rented office space and car pool.
The house itself is well planned with a flexible layout offering a range of technologies and features to achieve a high environmental performance.
The urban design approach encourages good place-making whilst allowing the terraces of houses to face towards the south for solar access.
The community garden in the centre of the scheme and the design of the house - it can be used as a north or south entry type - create an urban block layout that offers a sense of community and good natural surveillance of the external public realm and semi-private garden.
The image is striking and the layout of the home spatially interesting; using a central space as a ventilation 'chimney' and visually connecting all floors as an internal courtyard gives the project an international flavour.
A basement pantry, storage and sun-hat are additional interesting features.
2nd place - Beyond Code 6.
This scheme is rich in ideas, from the area strategies to a well considered house design.
The site wide strategies addresses transport, waste, water and lifestyle, renewable energy sources and includes a wind-farm and a CHP plant and district heating and coding, fuelled by bio-fuels.
Bio-gas is used to generate gas for cooking and the proposal includes a Green Community Officer to advise on lifestyle issues, a site wide extranet and information packs to address the education of citizens.
The urban design issues are well addressed with particular emphasis on house types that face east/west and yet have a south facing element.
The courtyard has the potential to be a secure and private space if the car parking ratio is in line with site wide strategies.
The house type is designed with a central service core and warm and cool spaces as fixed and repetitive elements of the plan.
The constant party wall dimension allows a repetitive structural timber glulam system.
The environmental performance is considered through the introduction of rammed earth and Hempcrete blocks and an earth cooling passive stake duct drawing pre-warmed or cool air through the building.
Micro-generation of energy and water saving and recycling measures are included.
The passive solar sunspace adds character to the facade and is made workable through the use of solar shading.
The design has a raised floor level and use of screw piles is an appropriate response to flooding risks and allows space for cold storage and recycling below the suspended ground floor.
3rd place - Adaptive Communities.
This scheme addresses the issues for wide area and local energy generation and emphasises the need for adaptive homes that address the changing circumstances of the occupants.
Site wide strategies include combined heat and power, wind turbines, grey water storage/reprocessing and local recycling centres.
The community energy generating centre makes good use of the economies of scale in energy production.
Similar concepts are reflected in the local urban block for micro-generation and storage, waste, recycling and incorporation of heat pumps.
The urban design approach of creating a conventional urban block works in principle although the gap in the southerly edge of the block could have been strengthened.
The design of the homes address the need for extendibility and adaptability to allow for changing lifestyles and family circumstances during the life of the building - provision of a frame structure retrofitted or built in at the outset aids sustainability in the broad sense.
The use of rammed earth, locally sourced clay and brick, blown help and other natural materials with a framed structure, scores highly.
SUN-Home.
The Sun-Home scheme examines the typology of the home and challenges the approach in the Code for Sustainable homes which does not make use of solar gain in the calculation of environmental performance - a valid argument.
The use of a wide fronted house - a popular type - offers opportunities to explore the type plan with more invention than the traditional narrow or medium fronted house.
The use of a trombe wall and thermal mass to aid the thermal performance of the building shows a break with convention and the wide frontage house lends itself to a large photovoltaic array.
The sunspace to capture winter heat works well as a design feature and as an aid to thermal performance.
The scheme scored very highly for the design of the home but did not address waste, water and materials issues in sufficient detail to comply with the Code requirements.
The densities achieved through the use of a wide fronted house type fell below the brief requirements.
Keep It Local .
Entitled 'Keep It Local', this submission covered the issues very well and was only let down by the urbanity of the built form, which appeared ill-suited to the suburban location.
The wide area issues were ingeniously dealt with by Pig Power, the production of bio-gas from pig waste to power the CHP plant for heat, electricity generation for the development and local food generation to reduce food miles.
The use of summer cooling through stack ventilation over the grey water storage and winter warming by winter gardens and a grey water recycling strategy ensured the scheme would achieve a Code Level 6*.
Electricity generation to offset street lighting by devices in speed humps was another witty feature of this inventive and well presented scheme - one that would fit well in an urban environment.
Code for Code 6.
It was refreshing to see an approach that was specifically aimed at the housebuilders and addressed the issues from their perspective.
The layout and approach is based on good urban design principles of perimeter blocks, parking courts and enclosed overlooked gardens.
A workmanlike approach to carbon neutrality has been applied based on 6 principles of sustainability: modern methods of construction, minimum heat loss, thermal stability, ventilation, renewable space and water heating, renewable electricity generation.
The use of MMC highlights a potential conflict between light and heavy weight construction and the Code requirements and the need to streamline production.
The six principles set out in the strategy to meet Code level 6* are simple and realisable within a cost constraint.
The use of rammed earth in the timber frame seems to be at odds with the buildability principles.
The simplicity of the solutions is appealing but the architectural form is compromised as a result.
C6 - ABC.
The contribution from a Part 2 student team offered some interesting perspectives.
The team used cutting edge innovative technologies as an alternative to the requirements of the Code, focuses on renewable technologies to address embodied energy in the production of homes rather than the energy consumption in use.
The use of natural materials, such as paper technology and rammed earth, provides a refreshing departure from the norm.
The use of Papercrete as a construction material is particularly innovative.
The issue of embodied energy in the manufacture of the home was a unique issue raised by the team and adds to the debate about the definition of carbon neutrality.
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