Clay Hill, Lavenham

The intention of this application is to create a new house which is zero carbon, truly ground breaking and one which enhances its landscape setting and makes a positive contribution to the local community. It will be an exemplary building of local and regional significance, meeting the highest standards of design and sustainability.

The proposal has been conceived through a close collaboration between the farmer and landowner, Modece architects and the Landscape Partnership. All three parties have a sound understanding of the Suffolk landscape and sustainability as well as a commitment to high quality design and implementation. The result is a design concept which enhances its setting and ensures that it will enrich Clay Hill Farm and the surrounding area as well as providing a much needed demonstration of the principles of sustainable development.

The concept for this new ecohouse was discussed informally with officers within the planning department and the proposal is being put forward as a PPS7 exception submission.

The proposal is not just for a zero carbon dwelling but also for a lifestyle which is entirely dependent upon its agricultural setting. The site is defined as the area immediately around the new house but the blue line identifies that the whole of the Clayhill Farm land holding will contribute to the project being deep green with an emphasis on low impact farming.

Project Planning History

This application is a resubmission following refusal of planning permission in May 2010. The refusal refers to the design not being sufficiently groundbreaking to meet policy PPS7.

The initial proposal was submitted in 2009 when Babergh Policy HS41 was still in place, and at that time the officers were extremely enthusiastic about the project.

Policy HS41 was removed from the Local Plan in June 2009, and following that the design was reconsidered under PPS7. As part of this process, Babergh’s planning officers took the scheme to Inspire East’s Design Review Panel to obtain an independent view. Inspire East’s review was generally positive and supportive, but it did stress that the building should be more visible in the landscape.

The building was then redesigned to take account of Inspire East’s feedback, and it was eventually presented to committee in May 2010, with a recommendation for refusal. That recommendation was followed by the planning committee.

Since that time the design has been re-appraised, and significant changes have been made. Further consultations have taken place with the successor to Inspire East, SHAPE East who were even more enthusiastic than previously and felt that only minor modifications were required to bring it up to the standard required by PPS 7. It is now, in our view, outstanding, groundbreaking and innovative as well as being zero carbon.

A representative from the Babergh planning department was present at the review panel. It supports the principle of the project and suggests certain adjustments to the design which have been incorporated in the modified scheme now before you.

Sustainability Features

Code for Sustainable Homes – Delivering Level 6 in a measurable way

It is possible to predict the performance of the house as measured against the criteria outlined in the Code for Sustainable Homes. These criteria are in subsections 1 – 9 as follows:

1 Energy and CO2 emissions

2 Water

3 Materials

4 Surface water run off

5 Waste

6 Pollution

7 Health and Well Being

8 Management

9 Ecology

Category 1

The most significant section is, as would be expected, category 1 which covers energy use and Carbon emissions.

The proposal is to construct the outbuilding from locally sourced timber and straw bales, coating the bales with locally sourced hemp mixed with English hydraulic lime to achieve a thermal performance of around 0.1w/mK. The main house will be constructed using timber framed construction with locally sourced timber and lime-hemp . Walls will be clad in timber and the overall thermal performance will be 0.131w/mK. Airtightness is guaranteed because of the continuous lime-based construction which protects it from unwanted air infiltration. The breathability of this form of construction ensures that the fabric remains dry and heating is therefore only required on occasional days to heat the internal air.

Floors will be constructed of timber, sealed from the underside with airtight breathable sheets manufactured from wood pulp, and finished on top with locally sourced timber.

Roofs will be constructed of locally sourced timber, insulated with locally sourced hemp fibre batts and clad with zinc.

With a well detailed external envelope the building will be sufficiently airtight to allow it to comply with emerging EU standards known as Passivhaus. These will, in due course, be adopted as part of the Code for Sustainable Homes. The design will meet the standards of Code level 6.

Other factors appearing under category 1 are:

Internal lighting will be from LEDs and the whole house will be lit using no more than 100 watts.

Clothes drying will be on washing line outside, or in the boiler house in wet weather

White goods will be A or A* rated

The house will be fully operated using zero carbon technologies

The house has a home office

Cycle storage is catered for

The design will attract full marks

Category 2 Water

Indoor water use will be driven down to 80 litres per person per day, through the use of highly water efficient appliances, spray taps, low flush toilets (or better still composting toilets). Drinking water will be provided from a new borehole, with all other water being rainwater.

External water use will be rainwater only, and a large underground tank will store a minimum of 10,000 litres for this purpose.

This will attract full marks.

Category 3 Materials

Environmental impact of materials covers the embodied energy of the chosen materials. The house will use predominantly natural, locally sourced materials which are generally carbon sinks, and this section will therefore attract the full amount of points possible.

Responsible sourcing of materials is a given bearing in mind that they satisfy a deep green agenda, with an emphasis on local.

This will attract as near to full marks as is possible.

Category 4 Management of surface water run off

This section assumes that surface water has to be disposed of and that it is therefore not a problem but in fact a valuable resource. By collecting surface water from all roofs and using it in the building, there will be no surface water run off. All paths will be constructed of porous materials, principally crushed limestone or local gravel which allow water to enter the soil naturally in order to recharge the aquifers.

This approach eliminates all flood risk and full marks will be awarded.

Category 5 Waste

Waste will be viewed essentially as a resource with all materials that can be recycled or re-used not entering the waste stream.

Household waste is generated principally from suburban consumer led lifestyles. This house will be largely self sufficient and packaging will be almost non existent. Any waste that cannot be disposed of on site, either by composting or burning will be sorted and disposed of through the normal Local Authority waste stream.

Construction using natural materials has been shown to hugely reduce waste. A number of sites have been built by the architects without the need for skips, with small non-recyclable waste being collected and taken to a recycling facility for disposal at the end of the job. Measurements have shown that about 80 – 90% of normal construction waste is eliminated.

Composting is de rigueur – human waste will be composted after liquids have been run through a reed bed, and this waste will be disposed of in the coppiced woodland, enriching the soil and stimulating growth and carbon uptake.

No bonus points are awarded for this approach so the house will only score full marks in this category.

Category 6 Pollution

Global warming potential of insulants scores only 1 point (which indicates the strangle hold corporations have on the environmental agenda). Natural materials ensure that carbon is sequestered, making this category better than zero. Again no bonus points are given for this.

Nox emissions are the one area where the CSH shows illogicality. Wood fired heating is classed as zero carbon, but penalty points are given for its nitrous oxide emissions. High efficiency boilers reduce the nox emissions significantly, but the mismatch between zero carbon and nox makes it impossible to score full marks for this category. The points system fails to take account of locally sourced fire wood and assumes road miles which reduce its score. In reality the firewood will be produced on the farm, and the house will therefore be off-grid.

Category 7 Health and Wellbeing

Good levels of daylight, good sound insulation (natural materials improve sound insulation because of the sound absorbing properties), private space which is a given in a single family home on a farm, and lifetime homes which has been factored in because the house is on one level will all allow full marks to be scored in this category.

Category 8 Management

The nature of a self sufficient home leads logically to self build with a vested interest in the owners having a full understanding of the efficient working of the building. Manuals are irrelevant in this case.

Any building workers will be controlled by the owners, and will have no impact on neighbours who are hundreds of metres away.

Site impacts of the construction is again closely controlled and will score full marks

The house will be protected against unwanted intruders.

Full marks will be scored for this category.

Category 9 Ecology

The site currently has a low ecological value as predominantly arable farmland mainly with potential for skylarks to nest. The ecological enhancements proposed through the introduction of many new habitats will attract full marks.

There are few existing ecological features and existing ponds hedges etc will be protected.

The site’s ecological value will change and be hugely enhanced

The building footprint is all on one level so marks will be deducted for this.

As full marks can only be obtained for buildings of 3 storeys or more it is impossible to score maximum points for buildings of this kind in rural areas. The entire Code is designed for urban and suburban sites and full marks cannot, therefore, be scored in this category.

An outline of the innovative nature of the Building Services

The very small amount of heating required to maintain comfort levels in the house will be generated by burning home grown logs harvested from the newly planted coppiced woodland, and the managed hedgerows. Wood is burned in a high efficiency boiler (93 – 95% efficiency with minimal off gases) to provide heating and hot water. A wood fired cooker installed in the kitchen will burn logs and operate at similar efficiencies to the log boiler.

Solar hot water heating will provide hot water for a large part of the year.

Electricity will be generated using photovoltaic cells, which are now finally cost efficient. The electrical demands placed on the system will be scaled right back through the use of ultra low energy lighting, and where possible appliances will operate using DC to further reduce power consumption. Currently available LED lighting means that the whole house could be lit using no more than 100 watts and the total peak power demand would be well within the generating capacity of the PV cells. Surplus energy would be dumped into the hot water system, and a large volume of stored hot water would even out the peaks and troughs in electricity generation.

The airtight fabric will mean that unwanted heat loss through draughts will be insignificant, and all heating will be used purely to heat the internal air within the building, rather than the surrounding countryside. The use of natural materials will ensure that the building fabric remains dry, and energy use will be further reduced. The standards applied in Passivhaus buildings and at Clay Hill Farm is for heat demands to be below 15 KW hrs per m2 per year, a figure which most people can only dream of. Low energy ventilation heat recovery, using pre-warmed incoming air which passes through earth pipes sunk 1m down below ground level, ensure that the airtight building fabric does not result in unhealthy indoor air. Air change rates of around 0.5 of the total air volume per hour are achieved using these technologies.

Design Process

How the design meets PPS7

In June 2011 the proposal was presented to Shape East, a design review panel based in East Anglia. Their report, found in the appendices, states that “the building was thought to be outstanding and to have the potential to raise standards of design more generally in rural areas‟.

Outstanding and groundbreaking design

An outstanding design has been achieved by a rigorous adherence to the design concepts from start to finish (see drawing 0805/13). The strong form of the floating element in the landscape is uncompromising from the west, yet behind this facade it is function that takes priority and the building performs extremely well as a farmhouse. It is this facade that divides the public frontage from the private living. It is hung as a veil to the sequence of spaces which connect the entrance through the house to the balcony. The glazing below the timber façade provides a beautiful moment created as only the feet of the occupants are visible until they step up into the living area. This western timber facade also wraps over to form the roof and overhangs the east wall. This simple gesture of one folded element enveloping an internal space ensures that the architectural form is uncomplicated yet striking.

The design of the building has been carefully considered to ensure that it frames certain key views out from the dwelling into the wider landscape (see drawing 0805/15). Every piece of glazing within the dwelling has been specifically placed to capture a view or allow day light in. The projecting zinc bay window which breaks the continuity of the west facade is orientated to perfectly frame Lavenham Church from the upper study level. In addition to this view to the west, a section of the storage building roof has been removed to allow a view out towards the north from the same room. The most prominent view is across the valley and to capture this the whole of the south wall of the living area has been glazed. The flexible space below also has glazing the whole way across the south face, however to increase insulation in winter and solar shading in summer there is a system of insulating screens which provide a flexible second barrier which can be completely sealed or removed if required. This produces a dynamic facade that will change throughout the day or year depending upon occupant preferences. This flexibility also extends to the internal partitioning of the lower floor. The space can be opened up as a large work room or sections of it enclosed to produce up to 4 bedrooms.

Arguably the most important part of this buildings outstanding design will be the extent of its sustainability. The building will provide the basis for the occupants to live and work the land in a highly sustainable manner, and therefore the building itself needs to reflect this level of sustainability. All of the systems involved, as shown in drawings 0805/11 and 0805/12, have been designed with the environment in mind, and the building should easily surpass Code level 6 as described above.

Innovation

The construction methods of the dwelling and associated storage building although contemporary are based on deep green building techniques. Over the last 14 years the architects have pioneered the use of hemp within the building fabric as an insulating and vapour regulating material. This research continues within the practice and will be applied to the proposed dwelling. It is hoped that the potentially high exposure of such a building would educate designers and clients to this new sustainable method of construction. The building would stand as an exemplar for sustainable architecture, contemporary design and a localised economy.

Grants

None

Green Lifestyle

Achieving a sustainable lifestyle on a working farm

Clay Hill Farm is an 18 ha arable farm and until now has been farmed as one block producing a single crop each year. Part of the farm has been cropped organically for the last 2 years with the aim of extending the organic principles over the whole farm.

The concept of re-instating the post enclosure field boundaries arises from the understanding that organic farming and the promotion of biodiversity is better suited to smaller field sizes.

The heavy clay land on the western edge of the farm (part of Pump Field) is ideally suited to coppiced woodland. It will be planted with ash and hazel and harvested regularly to produce firewood, pea and bean sticks, thatching materials etc. There are other small areas and field corners where drainage is poor and these also suit woodland planting and pond creation.

The five fields to the north of Clay Lane will be cropped in rotation following the East Anglian tradition of:

Year 1: Long straw winter wheat for thatching and milling

Year 2: Spring cereals for malting and local use

Year 3: Pulses and legumes – winter and spring beans and peas

Year 4: Spring Wheat for milling and also possibly for thatching straw

Year 5: Vetch/clover mix for sheep grazing

The grassland to the south of Clay Lane will be grazed by a resident flock of sheep providing meat to the local market. The pasture will also provide for late cuts of hay.

The area of land immediately to the north of Clay Lane within the fields known as Great and Little Burches is the lightest soil on the farm and suited to field scale vegetable production.

Further to the north is the original hop field, and the latest moves to promote hop growing in Suffolk suggest that this will be a perfect location for them. There is now a local market for organic hops, and together with malting barley they will be available to the increasing number of micro-breweries springing up in the area.

One of the interesting differences between small scale organic and agri-business is the level of employment. This farm will re-connect with the local community, providing opportunities for manual work in the coppiced woodland as well as in the vegetable and hop fields. Thatching straw will be cropped and used locally, and indeed there is already a link with a local thatcher who lives next door to Clay Hill Farm.

Another benefit of the small farm is that smaller machinery can be used which is both kinder to the soil and gives greater flexibility to the timing of cultivation as well as being more sensitive to the needs of wildlife. This sort of machinery is easy and comparatively cost effective to source, and reduces the growing tendency towards scrapping equipment after a few years.

Evaluation

This proposal has been carefully researched and designed to restore and reinvigorate Clay Hill Farm, its landscape, biodiversity and public access.

It will bring a new life and purpose to the land holding, enhance the setting of the Lavenham Conservation area and this part of the Special Landscape area.

The new farmhouse and associated buildings will not dominate the landscape but sit comfortably within it. This has been achieved by careful siting with appropriate and high quality architectural design.

But perhaps most importantly – there will be an overriding need or purpose for this new farmhouse house because it will be an integral part of the way Clay Hill Farm will be managed. The return to more labour-intensive farming requires those responsible to live on site.

This house and the farm also have the ability to make a significant contribution to the future debate on low energy living. They will contribute to the wider community by providing for the needs of local people through improved access, supply of food and fuel and potential building materials. They will re-establish the link between the community and the soil.

Suppliers and Professional Services Used

Modece Architects, HARTEST, Suffolk IP29 4ET

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