Code for ‘Upgradeable’ Homes

If adaptable pattern book house types is key to ESP developments, then we need to examine the relationship between the design of these and specifically approved house types as applied within the Code for Sustainable Homes. Ian Abley argues here that a variation in the Code for Sustainable Homes to better address ‘approved house types’ may be needed in order to focus more on ‘upgradability’ as an element of sustainability. MK

Ian Abley’s Summary Code for Type Approved Homes – click here to download PDF

The definition of “Dwelling Type” in the Code for Sustainable Homes appears to frustrate housing type development as house builders have sensibly understood them. Namely, that “types” are abstract but scaleable house and flat models that can be situated on any site, within obvious technical parameters. The CSH “Dwelling Type” is not sufficiently typological. This seems to frustrate a pattern book approach to planning. To make the CSH more of a Code for Type Approved Homes it is necessary to separate the 9 Code categories into sub-sets of the 34 issues that:

• can be generalised in the technical design of non-site specific house or flat types – 13 issues

• contractors will need to managerially control when the homes are to be built – 3 issues

• show how the typological designs must be formally and spatially situated on any plot of land – 7 issues

• can only be assessed when the topology of the specific site and the demands of the planning system are clear – 11 issues

The sub-set of topological issues must be minimised if designs are to be worked out and prototyped. The other three sub-sets of issues, or just over two thirds of the Code in typological, managerial, and territorial issues, may be pushed as far as commercially achievable by individual house builders before sites are developed. Out of the 104 credits to be worked with by designers that gives the following sub-sets:

• Typological issues – 45 credits, highly subject to the development of SAP 2009

• Managerial issues – 6 credits

• Territorial issues – 13 credits

• Topological issues – 40 credits, including all credits in the materials category requiring use of the Green Guide

The issue is when design can happen, and how few designs are needed to produce the widest range of developable solutions. It is possible to consider the Code as a question of meeting the Local Authority Building Control system of National Type Approvals Certification (LANTAC), giving economies of scale to house builders. This has to be done making assumptions about solar orientation in the Standard Assessment Procedure 2005, which is the basis of the current Building Regulations, and which will become a more important aspect of SAP 2009. The policy risk to be averted in the next four years is that SAP 2009 is allowed to undermine the need for a type approvals process.

Emphasis is then placed on improving the building envelope, in particular for better thermal and acoustic performance, and with the consequent need for more efficient building services. These will be integrated around the water based services, the mechanical ventilation, and the lighting systems, and will be physically separate from the air tightness of the building envelope. Since services need to be changed more rapidly than the building envelope, or the structure, the services should not be buried in inaccessible places, or run through construction tested for air tightness at the time of first fit-out. These are technical and organisational aspects capable of being prototyped and improved iteratively in a programme of research and development devoted to achieving a sequence of type approvals. The basic point being that over a 100 year life structural envelope, the kitchens, bathrooms, toilets and utility rooms, will all be upgraded on 10 to 15 year cycles as they wear out, become technologically obsolete, or fall from fashion.

The materials category may contain 24 of the 40 credits that are topological, but they are weighted low in importance in the CSH, as of October 2007. At the very maximum the materials category accounts for 7.2% of all the available points. There is then no need to be excessively concerned with the impact of local variations in the 13 point Life Cycle Assessment criteria that stand behind the Environmental Profiling ratings of the weighted Green Guide. No need either to worry too much about of the local uncertainties of “responsible sourcing”. These issues must be resolved when substitutable structural and architectural choices are made during planning applications. If they have to be determined too early in house and flat type development the misfortunes of the planning process or competitive construction product manufacturing can necessitate a complete re-design. Repeat fees for LCA practitioners undoubtedly, but the Green Guide is hardly an arena in which designers or construction managers can respond creatively to clients.

However that requires the weightings column to be fixed. If the materials category is allowed to be re-weighted in importance at any time in the future, the ability to design housing development typologically will be reduced. If weightings are fixed, then why have weightings? Why not just have scores out of 100 points, with a maximum of 4.5 points in the Green Guide as a mandatory entry level requirement, and an optional 2.7 points for the “responsible sourcing” of structural and architectural materials. If there were only points then, as defined by the Code, the housing design problem would be expressed as:

• Typological – 14.06 points at Code 1 and 49.86 points at Code 6 – with the need for SAP development to focus design

• Managerial – 3.13 points at Code 1 and 6.27 points at Code 6 – with more points at Code 1 for better managers

• Territorial – 15.84 points at Code 1 and 15.84 points at Code 6 – with the same design goals at all Code levels

• Topological – 3.33 points at Code 1 and 18.46 points at Code 6 – with most to gain in landscape and day lighting design

While CSH weightings remain unchanged, the greatest design advantage is in typological research and development. If weightings change, or other items are added to the 9 categories and 34 issues, a lot of design effort in pre-planning stages of development might be abortive. If the Code remains constant, then house builders may concentrate on the sophistication of their national house and flat types, in advance of planning approvals, with good building envelopes and integrated, upgradeable building services. They can also be maximising the point scoring abilities of site management, finding less bureaucratic ways to produce typologically designed housing, developing the planning pattern book as a site manual. House builders can do this largely unaffected by the commercial uncertainties of land acquisition deals, aesthetic preferences, and ongoing supply chain negotiation. That is true through to the higher Code levels up to 2016, by which time, if the CSH remains unrevised, some minimal topological issues will need to be better understood, such as day lighting and the importance of architectural fenestration.

That may suggest that house builders have to focus more on landscaping as ecological enhancement from Code level 4 onwards. A better landscape offers a maximum of 9.32 points, more than twice the top value of any combination in the Green Guide, and can be seen as more of a design opportunity and marketing advantage than limiting materials options consequent on protracted and not inexpensive construction Life Cycle Assessments. Also a landscape lasts, and matures. A complex LCA assessment on a “Dwelling Type” that within the short term may be changed unrecognisably, either by extension, adaptation, or the upgrade of kitchens, bathrooms, toilets, and utility rooms, seems like a weak investment of time and effort.

So the summary is this…

• Concentrate efforts on developing stronger, popular house and flat types that will assist with improving the construction management process, and which anticipate all declared planning policy issues to be formally and spatially addressed within and around the home.

• When the time comes expect to have to greatly improve the landscape on the specific sites that types are arranged into, to create a new and attractive local topography, since that is money well spent in market differentiation.

• Always keep structural and architectural options open on materials so that development programmes can respond to changes in the planning approvals process, to local demands and individual choices, and so that commercial competition can be maintained in the supply chain.

What is needed is a Code for Type Approved Homes. The Code for Sustainable Homes shows how that might be achieved. Forget “sustainable” and think “upgradeable” when designing repetitive but architecturally variable house and flat types for all sorts of new landscapes.

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