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Comments on the proposed new Design Principles for Letchworth

The LGC Heritage Foundation’s preview of the draft Design Principles which govern the changes householders can make to their properties have really got us thinking. Many of the problems Ebenezer Howard wanted to solve when he set about creating our Garden City are still relevent today. The Town & Country Planning Association (TCPA) are the modern day incarnation of the Garden City Movement and their manifesto recognises that climate change and resource depletion are two vital challenges we must address in the way we plan our towns and organise our communities. Personally, I feel Howard would agree with the TCPA and encourage pioneering action to find solutions to lessen our impact on the environment. I wonder what he might make of the Heritage Foundation’s restrictions around energy improvement measures to preserve the town’s appearance.

Click on “read more” below to see our detailed response – comments encouraged!

September 2013

1. General Comments

1.1 Transition Town Letchworth’s response to the ‘preview of the Design Principles for Letchworth’ primarily purpose is to identify and challenge any proposed design principles which will prevent home-owners from optimising the energy efficiency of their homes.

1.2 Improvements to existing homes are subject to Building Regulations Part L1B, Conservation of Fuel and Power. The design principles need to refer to and be in line with Building regulations L1b[1]. Although there are conditional exceptions for those Letchworth homes in the conservation area, even for these, there is still a requirement to improve energy efficiency as far as is reasonably practical. Insufficient thought has been given to how homeowners, who need to renovate their homes, will be able to meet building regulations and the design principles as currently proposed. It is not hard to envisage scenarios where compliance with the design principles will mean failure to meet building regulations.

1.3 There is a conflict, implicit in the proposed standards, between the need to improve the housing stock, i.e. to be more carbon neutral, and the desire to preserve the original housing legacy. On the one hand the standards require new builds to be up to modern standards while existing properties cannot be modified even when changes are cost effective and eco-friendly. For example, the Government expects its Green Deal to support people to make older properties more energy efficient, but residents in Letchworth Garden City will not be able to implement many of the changes that are included within the Green Deal[2] .

2. Detailed Comments

Character Areas and Exceptional Homes

2.1 The heritage character area document states that there are now two character areas and also introduces the idea of exceptional houses. Then throughout the document most pages contain a box stating that owners of exceptional houses should contact the HF’s Estates team if they wish to make any changes. The reality is that 1,757 home owners have no clear rationale as to why their homes have been singled out and no clear guidelines on what they can do with their homes. If the principles being applied for these homes cannot be written down how can one be sure that there is consistency? Rules should be written down and shared if there is to be transparency on how one judges whether an alteration is reasonable? We are concerned that too many houses are being singled out and will be prevented from making improvements which will reduce their carbon footprint. We are also concerned that the split between Heritage and Modern is wrong; too many estates are included in the Heritage area.

2.2 A few of the houses listed as exceptional houses are in modern areas and are of modern design, for example, those on Bedford Road. Yet no mention is made of exceptional houses on the character area page of the Modern Character Area booklet. If there are ‘exceptional’ modern character area houses these should be addressed within the context of the modern area guidelines.

2.3 In these design principles the HF seem to have gone from the three character areas which covered all houses to something less clear. The HF is clearly trying to preserve the green spaces, planting and open feel of the roads and streets throughout the town, which we fully support, and requirements around this do not change by character area. Then the HF is trying to preserve houses to different extents depending mainly on their age. If the HF had not started with the idea of character areas, I doubt it would have gone for the breakdown in documents that we have. If it is in fact the age / build type of a house that is important as to how it is considered, then this should have been the start point for structuring a publication. The majority of the guidance in the two character area documents is identical, so it would be easier for all concerned if the HF maintained one document and just made distinctions between property types on the rare occasions when the guidance differs. This approach would help to ensure that wherever possible all homeowners are being treated equally.

2.4 We note that on streets there are houses which would have originally been identical in design, with some of these houses considered exceptional houses while others are not. Given these apparent discrepancies it is important that householders are provided with a mechanism to question and if necessary appeal their exceptional house status. Owners of ‘exceptional’ houses might have thought that such a status was complimentary or an asset. For many people, the awarding of this status is seen as additionally restrictive. Any ‘advantage’ should be made clear to the home owners.

Extensions: Rear, Side and Front

2.5 One of the characteristics of Letchworth is the little differences between houses which are in groups. If an extension is undertaken by one resident which will improve the energy efficiency of a house, for example a porch, this should be allowed and in time other houses may follow this good example.

2.6 The ‘design principles’ state that rear extensions are favoured, however, there are problems with rear extensions that may mean it is not the best solution for extending a house. Firstly, the most useful garden areas are typically at the rear of a house and not at the side which is often shaded. Rear extensions can also lead to long rooms with poor natural light with health and energy implications. Have these issues been taken into account when producing these design principles?

2.7 Extensions will often improve the insulation of an external wall from one with no cavity, or a difficult to fill cavity, and hence poorly insulated, to well insulated walls. Thus suitable extensions on any face of the house should be encouraged. The 2m and 1m extensions rule from the boundary are too rigid. If the property has a 2m view through to the back (either on one side or by summing the views through on either side of a house) and detached houses will remain detached by a proposed extension the extension should be acceptable irrespective of where the property boundaries lie.


2.8 Porches provide an ‘air lock’ between the cold outside air and the warm interior. Retro-fitting porches should be encouraged and there should be enough room for more than one person to transit without having both doors open simultaneously. Hence the outside dimension of 1.2 metres is unnecessarily restrictive particularly as walls now need to be ‘thicker’, 1.5 metres is more practical.


2.9 If garages can be placed on the side of a house they help with insulation as they can enclose part of a single brick external wall. It also helps ensure garden space is maximised and shadow reduced on neighbouring gardens from the garage pitched roof. Setting garages back necessitates more hard standing as driveways are longer, which negates any green vistas.

2.10 Our expectation is that electric cars are the future. More cars will be kept in garages to charge them, but people also need to keep items such as workbenches and bicycles in garages. Has this been given any consideration in the 6m length restriction?

Loft Conversions

2.11 Windows provide free lighting (during daytime) and hence roof lights should be in sufficient numbers to provide adequate lighting rather than to be ‘kept to a minimum’ in loft conversions. Flush windows and sun tunnels should be acceptable on the front roof of buildings when designed to complement with the existing house.


2.12 There are many examples of ‘heritage’ houses with uPVC or coated aluminium windows that fit in with the street scene. Wooden windows have ventilation energy efficiency issues and high lifetime maintenance costs. The tightening up of requirements to state which material is acceptable is too restrictive and for many householders may be too expensive; the design standards should restrict themselves to appearance not material used.


2.13 UPVC doors readily meet modern insulation requirements and should be encouraged albeit with the caveat that they should match the original estate versions. The statement ‘Doors in uPVC will not be acceptable, unless……’ seems unnecessarily restrictive.

External Wall Insulation

2.14 With increasing concern about sustainability, climate change and rising energy costs the constraints included in the design principles on external wall insulation have increasing importance for homeowners. Preventing insulation is also out of line with the UK Government’s direction on sustainability. It is almost impossible to raise the energy rating of the bulk of the pre-war Letchworth housing stock up to an energy rating of B without some form of cladding. Internal cladding may be suitable in some circumstances but it is not the answer for the majority due to extra costs, technical limits (which can lead to mould), inconvenience (residents have to move out temporarily) and loss of space. External cladding is the answer for most. We reckon that there are around 7500 pre-war homes in Letchworth without cavity walls which need to be clad in the next 25 years (that is 300 per year). This Design Principle constraint does not just discourage that but positively prevents it happening or even starting.

2.15 We are particularly concerned with the phrase ‘all of the properties in a pair of semi-detached, terrace or group, collectively and simultaneously implement the works’. It is not reasonable to expect a homeowner or landlord to persuade others in their group of housing to implement wall insulation at the same time. For example, should a householder of a terraced home, who is perhaps about to fall into fuel poverty, but who has had a Green Deal assessment and may have obtained a loan or perhaps a grant, be prevented from raising their home to an Energy Rating B by this clause?


2.16 Regarding the use of timber on exhibition cottages and houses of historic interest, the use of softwood for barge boards and soffits is unnecessarily restrictive. Maintenance is ongoing and expensive. It is not a good building material and there are modern wood ‘look alike’ equivalents albeit more expensive. The equivalents are generally made of recycled plastics and their application should be encouraged.

2.17 Given that the existing clay tiles on the early garden city houses are reaching the end of their life, encouraging householders to use reclaimed materials could be considered poor practice (see page 16 of the Old House Eco Handbook written in association with the Society for the Protection of Ancient Buildings). If householders use reclaimed tiles they are likely to experience ongoing problems with their roofs.

2.18 Modern roof insulation requirements have made roof insulation thicker, thicker than most rafters. Roof heights, should be permitted to increase to allow for this, e.g. with a constraint of one tile higher, as long as this does not adversely impact on a linked property.

Guttering, pipes and hopper heads

2.19 Guttering and downpipes are usually replaced because they have failed. If this occurs at the front of the building how can replacement be avoided? Failing to maintain these could lead to problems with damp in the walls.

Solar Thermal and Solar PV Panels

2.20 Limiting the erection of PV and solar water panels to the rear roofs seems unnecessarily restrictive. They are one of the more cost effective ways of reducing energy bills and hence helping the environment. They should, at the least, be permitted on rear and side facing roofs.

2.21 There is no need to put size limits on solar hot water installations, no-one will pay for more than they can use.

2.22 For solar PV, limiting the installation to 50% of the rear roof of the building, where they are out of sight, has no rationale. This size restriction is likely to make installing PV uneconomic. Having paid over the odds per kilowatt for a half size system, households with PV really will not want to pay over the odds once again to increase its size if the design standards around size become more lenient in future. Letchworth’s contribution to renewable energy should be maximised.

2.23 In the modern character area the aesthetics of panels on a single storey or chalet property need to be balanced with the considerable economic advantage of installing solar PV, particularly for older people who have a high risk of fuel poverty.

Wind Turbines

2.24 While wind turbines are permitted subject to certain conditions it seems unnecessarily restrictive to add the caveat that they may be prevented if they ‘unbalance the symmetry of the roof lines’.

Rainwater Harvesting

2.25 It is important that we conserve and use water wisely. Water butts are a garden feature not part of the houses architecture and their use should not be restricted in any way by the design principles. Indeed in the original drawings of early garden city houses it was usual to specify water butts for the same reasons.

3. New Housing Development Guideline Detailed Comments

3.1 Page 9 Sustainability – ‘All new dwellings must meet at least level 4 of the Code for Sustainable Homes’ unquote. This requires architects and builders to achieve at least 68 points in the coding system. This sets a good standard to aim for but does not include mention of, nor encouragement for, community eco/heating schemes.

4. Conclusions

4.1 The failure to recognise and adequately address how Letchworth is to make its contribution to reducing its carbon emissions and hence tackle climate change through improvements to its existing housing stock is an unacceptable omission in these documents. There is much of value that needs to preserved in Letchworth Garden City, but the houses covered by these design principles are not empty museum exhibits. They are homes for modern families trying to live in today’s world and the Heritage Foundation should not be preventing home owners from reducing their carbon footprint and lowering their fuel bills.

4.2 The HF is the guardian of Ebenezer Howard’s thinking, we should not forget that the housing was designed to attract people away from overcrowded, unhealthy cities and the unemployment of the countryside. The new design principles for Letchworth should be reviving Howard’s pioneering spirit with social comfort – the quality, environmental cost and financial cost of housing – given more importance than architectural preservation.

[1] Building regulations L1b includes the following (source: Society for the Protection of Ancient Buildings ‘Old ECO handbook’):

Existing houses will need to be thermally upgraded when:

· previously unheated / uninhabited spaces are converted, for example, a garage or loft is converted into a habitable room

· more than 50% of any thermal element is being changed or renovated. For example, more than half the wall is being re-rendered or clad, or -more than half the roof covering is being stripped and re-tiled. In this instance, the whole of that thermal element would need to meet the standard

· more than 25% of the total building envelope is being changed or renovated. In this instance, the whole building envelope would need to be improved

· the U-Value for an existing thermal element does not meet a defined ‘threshold’ value.

There is a conditional exemption for listed buildings, buildings within conservation areas and scheduled ancient monuments. These do not have to comply if it would unacceptably alter their character or appearance internally or externally. In addition, the building regulations have three extra categories that benefit from ‘special considerations’; locally listed buildings; buildings of architectural and historic interest such as those within national parks; buildings of traditional construction with permeable fabric that both absorbs and readily allows the evaporation of moisture.

[2] Following a Green Deal assessment, recommendations will be made on changes which can be financed through the Green Deal. This is highly likely to include wall cladding for properties without cavities. Internal cladding is undesirable because it reduces room size, moves the dew point inside the brick wall giving rise to condensation issues, and causes maximum disruption to the occupants. External cladding does not suffer these problems but the design principles are so restrictive as to make it almost impossible. That is, the architectural detail is required to be modified to such a high standard that it is not cost effective (e.g. windows, window sills, window and door headers need to be accurately replicated and moved outwards and in many cases roof eaves and gables have to be extended) and all the houses in a terrace or a semi-detached pairing are required to be clad together.

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