Connecting planning with building control
To Colin Davies, 05.04.2007
Dear Colin
To open our discussion I am writing with an argument to try to answer the question: why pattern books in 2007?
The Code for Sustainable Homes outlined by the department of Communities and Local Government in December 2006 has set an agenda for the next decade of housing development. Although a voluntary code - at present - it is clear that the British Building Regulations will be revised to require more highly energy efficient new construction, in pursuit of the stated goal of "zero carbon" housing.
The requirement for highly energy efficient construction is a technically feasible policy objective. The aspiration to make those buildings "zero carbon" first requires the Code for Sustainable Homes to be developed into a technical manual, and second, requires reliable domestic energy supplies to be developed, either through utilities companies, or at the point of demand. Whether sufficient "zero carbon" energy supply can be provided annually to meet the demand from new housebuilding is unclear at this stage.
What is certain, however, is that all new housing shall need to be built to better, practical, and commercially viable standards of design and workmanship to be approved by Building Control as highly energy efficient. The highest standard being Code Level 5, which requires a thermal performance equivalent to that of the Halley IV Antarctic Research Station. That thermal performance of not only floors, walls and roofing will require windows and doors to match, with a level of air-tightness 10 times better than is currently required by Building Regulations, and tested to CIBSE TM23, a test method developed for commercial buildings with air-conditioning.
An air-tight building envelope requires the habitable space to be adequately ventilated. At the domestic scale the air quality of the internal environment will need to be maintained using a mechanically ventilated heat recovery (MVHR) system expelling spent air from kitchen appliances, bathrooms, and toilets, without loss of all heat to atmosphere. In warmer weather the windows will need to be openable, or the MVHR system can be reversed into a cooling mode, like a domestic scale of air-conditioning. Or both - openable windows with the option of keeping them shut and using mechanical cooling.
In future all new housing will need to be an integrated system of structure, envelope, partitioning, fittings, and building services. This suggests a whole building approach to design, which can be realised using both on-site and off-site construction, in a range of architectural solutions, and capable of being upgraded with better building services and fittings, partitioned differently as the household changes, with a maintainable envelope related to a structure with a specified design life, which is in factored into the financing of the development.
There is an international body of research that shows the goal of highly energy efficient new housing, designed as an upgradeable, flexible, adaptable, maintainable, and extendable structure, is entirely possible. However no country, region, or locality has ever produced housing of that kind on a scale sufficient to meet population and household growth. Britain is embarking on an industrial and social experiment over the next 10 years. Which is fine - if Britain plans for housing production and achieves that aim. My only criticism of attempts to plan for production is that 200,000 homes a year are being talked about, when we need 500,000.
There are critics of this high ambition. Those who argue that "zero carbon" is either necessary or uneccessary have a case to answer in the wider discussion of energy supply and climate change. It is worth making the clear distinction between "zero carbon" energy supply and energy efficient housing for that reason. For there is no objection to the engineering goal of energy efficiency. Those who say it is impossible to build British housing consistently to high standards raise numerous objections, all of which can be disproved by managing to produce Code Level 5 housing. It is that which should concern us.
It is no longer possible to submit a planning application without having designed down to substantial technical detail in pursuit of Code Level 5 performance. The technical demands of the Code for Sustainable Homes require arrangements of buildings on sites in relation to the sun and landscaping, floor plan types, floor to ceiling heights, and wall thicknesses that must be known to result in a Code Level performance before the planning application is lodged. Historically that is not the sequence in which housing designs have been developed and approved. It has so far been technically possible for land use approvals to be given to indicative building designs before they were made to work as construction.
That is no longer viable. The Code for Sustainable Homes points to a time when planning applications will be at risk unless the applicant knows from investment in research and development that high performance housing can be delivered on budget. In the commercial and institutional construction sector that might not seem too onerous. In housing it requires a resequencing of design development and approvals. There now needs to be a way of predicting a technical solution for Code Level 5 housing acceptable to Buiding Control and the planning committee at the time a site is being considered for development, if not before. Even before an end user client is known.
For the larger house builders this arguably means little more than retaining a stable of consultants who can offer whole building solutions of minimal construction thicknesses and building services at the planning stage. For smaller builders, or the one off applicant, those consultants cannot be retained, and will be shared on a project by project basis. For the various consultants there will be pressures to try to maintain more stable relationships with other consultants, and maximise repeat business from the smaller and larger house builders. At first that process may be awkward, but as experience of working towards the higher Code Levels becomes established consultants and builders will consolidate around a legacy of more or less successfully constructed whole building solutions.
However, that will only address the needs of the professional consultants and the commercial house builders interested in new housing development. For Housing Association clients, or speculative housing developers, both concerned with building housing in variously sized batches on larger sites, that will be a way through the Code for Sustainable Homes. Their only problem will be in securing larger sites, which may mean the protracted aggregation of many smaller sites, particularly in local authority areas with a legacy of housing types. They will otherwise be most able to negotiate through the planning approvals process, reliant on their consultants and builders to have fully anticipated the higher standards being required by Building Control over the next decade.
Higher performance specifications will not be so easy to manage for the individual, hoping to build a single home, or a small number of dwellings, on a single site, perhaps to replace an existing, obsolete or exhausted structure. The small percentage based fee for consultants on a small endeavour means that very little design time can be afforded to the individual client. The small capital value of the project will mean that larger builders will not be tendering for the work, which may reduce the chances of the individual client getting housing built exactly as planned within a limited budget. It will almost certainly mean that pre-planning consultancy and practical advice will be minimal, and absent at the time it is needed most.
If true - and I am happy to be proven wrong - the frustration of the multitude of smaller house building activities in Britain is a missed opportunity. The impact of the Code for Sustainable Homes may be to undermine efforts to raise the numbers of homes built each year, failing to appreciate that most housing is of a type in a previously developed locality. Many individuals want very similar kinds of housing, and very often the planning officers and their committees want some level of repetition too. For most of Britain it is possible not only to identify terraced, semi-detached, or detached housing types, repeating through various topologies, but to further identify localised aspects of design that give them a more distinct character.
Ian Abley 05.04.2007 (part 1 of 2)
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