Residential /
 
Eco house / Zero and near zero carbon house / Passivhaus
 

The practicality and cost of achieving energy efficiency is going to play an increasing part in determining the value of existing homes. Global resource depletion and the realisation that high energy costs are here to stay is generating a huge and growing interest in new-build low energy houses as an alternative.

In the world of low energy houses, what is the difference between an eco house, a zero carbon (or near zero carbon) house and a Passivhaus? There is a lot of overlap but here are some pointers:

Miller Architects Cross section through zero carbon eco house Wealden District

Miller Architects Cross section through zero carbon eco house Wealden District

An eco-house is a sustainable eco-friendly home for the future. The process starts with the choice of site, the orientation of the house and the location of windows to maximise seasonal solar gains coupled with the compactness of the plan. A ‘fabric first’ approach dictates that the walls, floor and roof are very highly insulated and the windows are triple glazed. Good air tightness and the elimination of cold bridges is also required. Allied to this is an understanding of how much energy has gone into all of the components which are ideally locally sourced.  The next consideration is the use of technology in the form of a ground or air source heat pump (GSHP / ASHP) for space heating and domestic hot water powered by battery power supplied by an array of solar PV panels. This can be combined with a mechanical ventilation with a heat recovery (MVHR) whole house heat recovery system that provides a balanced supply of fresh, filtered, heat recovered air to the living areas, whilst simultaneously extracting stale, moist, odorous air from ‘wet’ rooms. This system recovers a large percentage of the heat that would otherwise be wasted. Various possible combinations of these and other renewable technologies can be explored in terms of their up-front cost as a proportion of the build cost versus the projected pay-back period.

Like the name suggests, a zero carbon / or near zero carbon house produces, in theory, zero or near zero CO2 emissions by maximising energy efficiency and renewable energy. It is possible to go beyond achieving net-zero carbon emissions through a carbon negative approach that involves removing CO2 from the atmosphere by on or off-site tree planting.

Lastly Passivhaus. Passivhaus is owned by the Passivhaus Institute of Darmstadt, Germany which regulates certification. A Passivhaus must be designed by a certified Passivhaus designer, it must be computer modelled in 3-D and then computer modelled in the Passivhaus Planning Package (PHPP) which is a ‘bolt on’ to Sketch-up. The work must be tested during construction (eg air tightness) and signed-off by an independent accredited Passivhaus certifier separate to the main design team. So there is a cost to it. There is no requirement to obtain the Passivhaus ‘stamp’ on a project though the exacting Passivhaus requirements might be part of the architectural brief and the ‘stamp’ could be useful for future marketing.

Give us a call for further information and / or help with the planning of your eco house / zero and near zero carbon house / Passivhaus.

News /
 
The New NPPF
 
Angela Rayner 'will force councils to build houses if they miss targets'

Angela Rayner ‘will force councils to build houses if they miss targets’

In her statement of 30 July 2024 the Deputy Prime Minister Angela Rayner set out her plans to ‘get Britain building’ to address ‘the most acute housing crisis in living memory’ by means of a revised pro-growth NPPF which is out for consultation with adoption planned for late September. The government has pledged to build one and a half million high-quality, well-designed and sustainable new homes across the country within five years.

This has the potential to have major impacts on planning policy in Wealden. In early 2020 Wealden District Council voted to scrap its Draft Local Plan after a planning inspector concluded that it failed to meet the duty to cooperate and was unsound on a number of grounds. Some four years later on the 15 March 2024 the Council finally launched its public consultation on a new Draft Local Plan. However this is already in trouble as the government proposes to remove paragraph 226 of the existing NPPF and re-establish the requirement for all local planning authorities, regardless of local plan status, to continually demonstrate 5 years of specific, deliverable sites for housing. Up-to-date local plans are essential to ensure that communities have a say in how development happens and going forward all authorities will need to have a Local Plan in place that address a mandatory Housing Target arrived at using a new Standard Method.

It is to be hoped that as few as possible of the new homes are delivered by the volume housebuilders, whose speculative ‘identikit’ estates have wreaked havoc on the countryside and led to unaffordable and car-dependent executive homes. Imaginative architectural solutions are capable of ‘unlocking’ the value of sites within existing urban and suburban areas. Do not hesitate to be in touch if you require help with ‘unlocking’ your site.

News /
 
The Revised NPPF
 

The government has just published the latest version of the National Planning Policy Framework (NPPF) which sets out the latest planning policies for England and how these are expected to be applied.

Much to the anger of the volume housebuilders, whose speculative ‘identikit’ estates have wreaked havoc on the countryside and led to unaffordable and car-dependent executive homes, Michael Gove announced that the NPPF has scrapped requirements for councils to allocate Green Belt land to meet housing targets. The loss of Green Belt land is irreversible. I think most architects will support this move, not least because very few are involved in the delivery of these unsustainable predesigned boxes anyway.

The revised NPPF also includes sections on urban areas including the role new housing can play in regeneration and the support of local economies. Gove stated that the creation of new homes will be targeted on towns and cities where people want to live and work. I think most architects will support this too. In urban areas architects can bring their unique design skills to bear to release value even in the most problematic situations. No two urban sites are alike – all require an imaginative bespoke solution.

Farmer's market on East Grinstead High Street

Farmer’s market on East Grinstead High Street

Take, for example, my local town of East Grinstead in West Sussex which is undergoing a bit of a renaissance. It was always an attractive place to live on account of, amongst other things, its history, location at the top of the High Weald Area of Outstanding Natural Beauty, proximity to London, access to the south coast and its upmarket High Street. Now on account of the conversion of offices to low energy flats, other residential developments and the move to working from home, a car-free town centre residential ‘scene’ has developed. There are plenty of opportunities for this trend to continue  – most of which will require imaginative architectural solutions to realise them.

Latest /
 
Leighton House Museum
 

I visited the recently refurbished and extended Leighton House Museum in Holland Park last week.  The building, designed by George Aitchison and built in stages between 1878 and 1896, was the London home and studio of the celebrated Victorian painter and sculptor Sir Frederick Leighton.

It is fine example of late Victorian architectural design with ‘set piece’ interior spaces that reflect the obsession at that time with orientalism and the aesthetic movement.  The Entrance Hall, the Staircase Hall, the Narcissus Hall, the Arab Hall, the Library, the Dining Room, the Drawing Room and the Silk Room are all special in their own way.  As well as these spaces there are two functional first floor workspaces – the Studio and the Winter Studio – where Leighton created most of the paintings of his mature career.

The most impressive of these is the Arab Hall with its domed ceiling and fountain which was built to house Leighton’s collection of tiles collected during visits to the Middle East.  It is hard to see how this space could have been used other than for entertaining.

The Arab Hall and the Narcissus Hall photo: Royal Borough of Kensington and Chelsea

The Arab Hall and the Narcissus Hall photo: Royal Borough of Kensington and Chelsea

I always say that it is preferable to have a small number of special ‘architectural’ spaces in a house rather than a large number of box-like cellular spaces.  Leighton House takes this approach to extremes with almost all of the space being intended to entertain guests and impress clients.  Leighton remained a bachelor and one slightly odd moment is to visit his rather nondescript bedroom with its little single bed.  Apart from two servant’s rooms in the roof space and a butler’s room in the basement it is the only bedroom accommodation in the house.  Goodness knows where his guests slept if they wanted to stay over.  Perhaps none of them did.

Victorian art fell out of fashion very quickly after World War I and it is only in the last 50 years that there has been renewed interest.  One of the most famous examples of this low point was in 1963 when ‘Flaming June’, one of the most significant among Leighton’s classicist pieces which was painted in Leighton House, went on the market in London in 1963 for just £50.  It is currently on loan to the Metropolitan Museum of Art in New York where it will be on display until February 2024.

News /
 
Driving Using Both Accelerator and Brake
 

25 years ago a hugely influential government report entitled ‘Rethinking Construction’, also known as the Egan Report, was published.  It looked at the how the UK construction industry could adopt efficiency measures used in other industries such as automotive and aerospace. In the time since it was published the industry has moved a long way to implement the five key drivers of change: committed leadership, focus on the customer, integrated processes and teams, a quality-driven agenda and commitment to people.

But what about the government? The government has always used construction as an accelerator and a brake for the economy thereby denying the industry the stability it needs. The decision to mothball the redevelopment of the Euston HS2 station suggests nothing has changed. The whole HS2 project, which is the ‘flagship’ ‘levelling up’ project, has suffered cut after cut and will no longer make it either to the north or central London in the near future. The Euston project has been stopped during construction and mothballed for at least the next couple of years in order to cut costs and push them into the future. The scheme, which dates from 2015, faces another redesign following one last Autumn to reduce the number of platforms.  The main contractor had about 360 people working on site but many more employed at subcontractors and suppliers will have been affected. The design team was 600 strong with half of them based on site.

Euston HS2 Station image HS2

Euston HS2 Station image HS2

I know from experience that it isn’t possible to shave more than a single figure percentage off the cost of a project without a fundamental rethink of the design. Why has it taken 8 years to decide that the 2015 scheme is the wrong scheme? I can’t think of a more expensive way to ‘save’ money than to halt and redesign a project mid construction.

The government needs to ease up on austerity when it comes to infrastructure and treat it as investment to boost flagging growth and deliver on the ‘levelling up’ agenda.

Latest /
 
Including a Fitted Kitchen in a House Extension or Refurbishment
 

What is the best way to have a fitted kitchen designed, supplied and installed as part of a house extension or refurbishment project? I am often asked this as there are various approaches.

Island kitchen, Dormans Park, nr East Grinstead

Island kitchen, Dormans Park, nr East Grinstead Underwood Kitchens

One approach is to have the fitted kitchen fully designed and specified by the architect and installed by the builder as part of the contract works. This involves the architect specifying all of the components including the base and wall units, countertops, splashbacks, sinks, taps and equipment. Both the architect and the builder are paid for their services with regard to the kitchen.

Another approach is for the client to purchase the kitchen components outside the contract (either designed and specified by the architect or by a specialist) and provide them ‘free issue’ to the contractor who installs the kitchen as part of the contract works.

L-shaped kitchen, Forest Row

L-shaped kitchen, Forest Row Homebase KitchensHomebase Kitchens

Yet another approach is to have the fitted kitchen designed, supplied and installed by a specialist outside the contract after the extension or refurbishment work is finished. This avoids paying either the architect or the builder for any services with regard to the kitchen but has the disadvantage of pushing back the date when the kitchen is operational.

I have evolved an intermediate approach whereby the standard form of building contract is amended with a clause added requiring the builder to permit access during the final weeks of the contract (it is his site so he can otherwise deny it) by a specialist directly engaged by the employer under a separate contract. Subject to negotiation this approach can allow the client to procure a specialist kitchen design, supply and install ‘package’. The builder provides a ‘serviced shell’ for the kitchen (to suit the specialist’s design) comprising the finished floor, walls and ceiling plus capped-off services in the shape of hot and cold water supplies, waste, extract ventilation, gas, power and lighting.  The specialist then installs the kitchen into this ‘serviced shell’.  Finally the builder makes the final connections for the services and all fitted kitchen appliances and includes the kitchen in the project GasSafe and electrical certification.

Kitchen design is a personal thing for all clients in terms of the style and layout of the kitchen, the type and amount of equipment and the expense which can vary by up to a factor of ten. I think it is best for the architect to simply set the design parameters in terms of the location and general layout (such as an L-shape, galley, island, peninsula etc) and then allow the client to develop and finalise the design, supply and installation with a specialist.

Latest /
 
House Extension Cost
 

How much does a house extension cost in London and the south east?

My analysis of actual costs for competitively tendered projects by reputable local building contractors in the south east within commuting distance of London suggests a current ‘ball park’ figure of £3,000/m2 for a single storey extension and a further £2,000/m2 where there is a second storey. These figures are based on a full fit-out to a reasonable standard of specification including bathrooms. They will go up if the project is located closer to central London and down if the project is further out. Tender prices have been rising steadily over the last few years. The tender price inflation forecast in this month’s Building Magazine is for a 5% increase over the coming year however builders that I have spoken to are suggesting that it will be more than this. House extensions attract VAT at 20% and a client contingency of say 10% is advisable.

Single storey extension at 'Charwin' under construction

Single storey extension at ‘Charwin’ under construction

Whilst m2 area costs are a good guide, design complexity and the level of specification can make a big difference.  There are also project specific costs such as the cost of demolitions where required and the cost of other work within the existing house. The cost of the foundations can increase beyond the cost of the standard depth of one metre if the ground conditions are poor. External drainage costs can increase if extensive reconfiguration is required. If the design requires a structural steel frame rather than individual steel members this would be an extra as would the cost of a ground source heat pump installation with its associated ground loops and / or bore holes. The biggest single cost that is not included above is the cost of a new kitchen which can vary enormously. Several years ago I had two concurrent projects where the cost of the similarly sized kitchens differed by a factor of ten.

Two storey extension at 'Fir Tree Cottage' under construction

Two storey extension at ‘Fir Tree Cottage’ under construction

Architects provide ‘ball park’ estimates based on m2 rates but if cost ‘is of the essence’ a quantity surveyor or construction cost consultant / estimator can produce a more detailed estimate on an ‘elemental’ basis where every element of the project is costed. Typically for a project of this size clients opt to rely upon the architect’s estimate until the tenders are returned. At the end of the day it is the tender price at which a building contractor is willing to carry out the work that matters.

I am usually the starting point for a house extension project. The full architectural service is typically in three roughly equal parts which are concept design and developed design to Planning Application / technical design up to Building Regulations and tender / contract administration and construction to handover and close out. Partial services are available (eg just the first part or just the first two parts). I normally provide the ‘principal designer’ role as part of the architectural service. During the technical design stage the core team typically comprises a structural engineer to provide calculations for Building Regulations purposes, an underground drainage engineer to carry out the design for the underground drainage and an energy assessor to demonstrate energy efficiency in compliance with the Building Regulations. Consultant fees for this core team will typically be around 13% of the building cost. There will also be local authority fees for Planning (where required) and Building Regulations.

A house extension can be a viable alternative to moving house as it avoids the disruption and the cost of moving, stamp duty, legal and estate agents fees etc. On top of the desire for extra living space and bedrooms, information technology is driving a move towards living and working from home with the demand for additional space for a home office. As well as this the process, if handled properly, can be very rewarding.

Latest /
 
Permitted Development
 

Permitted Development (PD) rights are a bit of a minefield as the rules are often hard to interpret. There are frequently misconceptions about PD and these are the ones that I commonly come across:

  1. PD is what is permitted without planning permission. It is not necessarily as much or as good a solution as what might be available if a planning application is made and approved. So PD may not be the optimal solution.
  2. PD rights are often hard to interpret for a specific project and if a property is subsequently sold the incoming purchaser could seek confirmation that what has been built is indeed PD. Therefore in most cases clients apply to the local council for a Lawful Development Certificate which is in some respects similar to a householder planning application. So an application to the council may be needed in any case.
  3. PD rights are restricted in ‘designated areas’ such as conservation areas, National Parks (such as the South Downs National Park), an Area of Outstanding Natural Beauty (AONB) (such as the High Weald AONB) and for listed buildings. So PD may not apply.
  4. Building Regulations approval is still required. So a set of design drawings will be required in any event.

Always worth talking to your local architect to avoid a missed opportunity and/or a costly mistake.

Latest /
 
Listed Building Alterations and Extensions
 

We are carrying out increasingly more work on Listed Buildings which is a fascinating area of work requiring an understanding of history, context, local materials and techniques, crafts and culture as well as the usual combination of design skills, competence and experience.

Alterations and extensions to Listed Buildings require Listed Building Consent or combined Householder Planning Application and Listed Building Consent for the carrying out of any works whether internally, externally or within the ‘curtilage’ that would affect the building’s special architectural or historic interest.

We recommend that a pre-application consultation is had with the council as the best way forward in the first instance and this route is generally recommended by planning authorities.  It is a cost effective means of obtaining an ‘in principle’ response before significant expense is incurred.  Diagrammatic sketches, together with photographs, overlays and a site plan can be enough to illustrate the proposed use, scale, form, and external materials of what is proposed.

Good design can play a large part in the process.  Listed Buildings need not be preserved untouched, like museum pieces but proposed changes need to be informed and justified.  Preservation of the existing fabric can be coupled with a sympathetic, imaginative and ‘legible’ intervention that secures the economic sustainability of the building perhaps for several hundred more years of useful life.  Alterations related to the existing historic fabric and architectural features are likely to be more controversial than an extension which can be designed to ‘read’ separately in order to minimise the impact.  Similarly, an extension to the principal elevation is unlikely to be acceptable.

Applications for Listed Building Consent require to be accompanied by a Heritage Statement covering the evidential, historical, aesthetic and communal aspects of the Listed Building and what is being proposed.  This has to demonstrate how there will be both ‘less than substantial harm’ and a public benefit.  A specification and methodology are required to demonstrate that there will not be harm to the existing historic fabric.

At the end of the day some change is inevitable to ensure the continued use and enjoyment of Listed Buildings but professional advice from an architect is essential to avoid a missed opportunity and/or a costly mistake.

News /
 
PAS 2035
 
For years the writing was on the wall – diesel exhausts are harmful. It was clear that the days of diesel powered cars were numbered yet they continued to sell in great numbers. Until the penny dropped and they suddenly stopped selling with a collapse in registrations and residual values.

Adding 69.5mm of Kingspan Kooltherm K14 insulated plasterboard to a 215mm solid brick wall will result in a U value of just 0.25W/m²k Photo Kingspan

Adding 69.5mm of Kingspan Kooltherm K14 insulated plasterboard to a 215mm solid brick wall will result in a U value of just 0.25W/m²k Photo Kingspan

I predict a similar fate for energy inefficient houses where currently purchasers pay little, if any, regard to Energy Performance Certificates. The government has introduced a new Retrofit Standards Framework. Central to this is ‘PAS 2035 – Retrofitting dwellings for improved energy efficiency. Specification and guidance’. From June 2021 it will become compulsory for all certification bodies and TrustMark registered businesses to comply.

With new homes moving towards zero carbon, old homes will need to offer an increasing degree of energy efficiency if they are to sell. Energy efficient measures and the associated installation costs and costs in use will be a major consideration in valuing them. So factor these in when you come to buy and sell or you might be left with the bricks and mortar equivalent of an old diesel.