Building on the Green Belt

Paul Cheshire of the London School of Economics came to HTA last month and presented his thoughts on Building on the Green Belt. It was at once appalling and fascinating. I think it is worthwhile to explore ideas that are superficially appalling to analyse why they affect us in this way and whether our sensitivity to them is real or something we have learned without really absorbing the rationale behind it. The history of civilisation is full of bad ideas that were once held to be good ideas but which we now find appalling. By we, I largely mean Western civilisation. By bad ideas I mean racism, fascism, UKIP, factory farming…those sorts of ideas. What seems obvious to one generation can often appal the next one. Think about 70’s fashion!

Building on the Green Belt(BoGB) has come to attract the same strong reactions as some of those ideas above, whether one is for or against, there is no real middle ground. The cause against BoGB is is largely emotional and visceral, its ‘green’ land, the reasoning goes, so it must be nice, its surely full of woodland and trees, it harbours the last vestige of medieval connectivity with the ‘land’ that feeds us. We will all choke to death on the fumes of cars and buildings if we allow this to continue, etc., etc.,We are carpeting over England’s green and pleasant land and we mustn’t allow it to continue, or even think about allowing it to continue. Is any of this true?

The problem with all of this is that there is enough truth in it to make it believable to the average voter, and therefore completely toxic to our current crop of rather spineless politicians. Were BoGB to happen it will inevitably destroy some areas of land that have some ecological value, and will inevitably carpet over some of the ‘green and pleasant’ land. But the argument is more complex than this. By not BoGB we are curtailing the supply of land for housing in a way that was not envisaged when the legislation was enacted. We are in a period of chronic under-supply of homes and young people have little chance of getting an affordable home to live in unless we act to increase supply. London in particular is being constrained to the point where housing ownership is becoming impossible for young people on a normal wage.

To change the housing market we need to be building many more homes that we are currently building, this appears to be generally accepted. Some of these can be delivered in dense new apartment developments close to jobs in city centres. But high density development is slow to bring through the planning system and often controversial. On its own it won’t be enough.

I dislike the idea of BoGB as much, and possibly more than most, I prefer to design dense environments for people to live in, as I believe that high density living brings with it high-quality services. If I had my way we would all live in terraces or apartments and the suburban semi would be banned. Fortunately there are a lot of people who disagree with me and who want to live in the suburbs in a semi and they should have what they want. Shouldn’t they? Is owning an environmentally damaging house with four cars and garden in the suburbs an ‘inalienable human right’ or should it be classified as something that previous generations longed for and could afford, but which we cannot? Do we recognise that the costs of allowing everyone to own their own patch of grass two hours commute from where they work is neither good for them nor good for society as a whole?

To look at the figures dispassionately, 13% of land in the UK is Green Belt land. have produced a nice map illustrating the many designations of land used in England to prevent development. Their research demonstrates that we have built on approximately 10% of our land, leaving the remaining 90%, much of which is unavailable for development. The illustration of Green Belts around the main population centres demonstrates that they are doing their job of curtailing the growth of those centres, and putting pressure on nearby smaller towns to grow instead.

Unfortunately this land use planning strategy is not matched by an economic strategy that is helping to create jobs in those smaller towns. The result is a working population in the cities that must commute long distances to work and puts increasing pressure on the transport system. See here for statistics showing that a decade ago about one third of London’s working population commuted into London. One of the results of this has been the construction of more roads through the Green Belt, which has further degraded it, on top of the highly industrialised agriculture practised in most of the Green Belt which has denuded it of trees and wildlife. It may be green in colour, but much of it is grey in environmental terms, ecologically poor, with sparse areas of ecology poisoned by pesticides and curtailed by the machinery of the supermarket supply chain. Is it really worth protecting? Are we being realistic by calling it the Green Belt? Are we using the right yardstick to measure it against? Should we call it an Environmental Zone or Green Zone instead.

The decades-old principle of home ownership will soon be at an end unless these conflicting strategies are resolved. Land use designations including the Green Belt have become an inconvenient sacred cow that is preventing our cities from expanding. Growth is being pushed out to smaller dormitory towns, and pushing up the price of land outside the Green Belts to levels where starter homes require subsidy to be affordable. The policies discussed in the recent round of conferences include subsidies for first time buyers is a direct result of a set of planning policies that limit the opportunities for development.

I suspect that the Green Belt could be made smaller, more environmentally beneficial, and much more meaningful in real terms by being ‘masterplanned’ and ‘activated’ more thoroughly. The reality is that most Green Belt land currently performs little useful function other than to curtail development. Given that our wildlife population continues to plummet, we cannot argue that Green Belts have fulfilled a function of protecting wildlife. To live up to its designation Green Belts need to be transformed into places where nature can thrive and also be enjoyed by the urban population they are intended to support. A series of Environmental Zones surrounding our cities which contain leisure activities as well as a proportion of responsible farming, new woodlands, wind turbines, biodiverse places rich in ecology and protected by future generations and bounded by dense high quality homes seems to me to engender the best of both worlds. The costs of these changes would be borne by the sale of a proportion of the land for new housing.

Since many of these areas are already well-served by public transport little new infrastructure would be needed. The existing infrastructure is currently under-used as these outlying areas have not been able to expand since the transport network was installed decades ago. By creating jobs in these locations we would also reduce the need for expansion in the transport network and balance the current concentration of jobs in the centres of our cities with a new set of suburban desirable locations for people to live and work. The Green Belt was a good idea and it has left us a legacy of potential that we can use, but on its own it is not enough to guarantee a positive future for our major cities.

Louis Kahn Exhibition at the Design Museum

Hurva Synagogue

Hurva Synagogue

The exhibition on Louis Kahn currently being held at the Design Museum, London, is worth seeing for all students of architecture, young and old. Kahn’s place in the panoply of modern architects is well deserved and this exhibition demonstrates why. Much of the material is familiar to anyone with an interest in his work, but the revelation for me is a series of large scale wood models of his work created by the Vitra Museum in 2012. These large-sale models, particularly of some of his unbuilt work, bring it to life in a new way. Models of the unbuilt section of the Salk Institute at La Jolla show the sophistication of that design in a way that drawings have never done, a design that presages the Government buildings at Dhaka many years later.

The full size model of the Fisher House window seat shows how Khan was able to manage the transition from the large scale down to the smallest scale in a way that few other architects have ever managed. This model illustrates a dwelling that was clearly humane and inhabitable in a way that few other architects have managed. Somehow Kahn was able to focus on the essentials of each of his projects without bringing his ego to the table. A quality sadly lacking in the work of many of our modern ‘starchitects’ who appear to be lauded for bringing their egos to the table to the exclusion of anything else.
Fisher House Window (Vitra Museum model)

Fisher House Window (Vitra Museum model)

Kahn’s particular philosophy , which can seem so obtruse and difficult at a casual reading, was sophisticated enough to guide him towards the creation of buildings places that are both humane and monumental. His buildings are effortless looking because he cared about the mechanics of construction and was prepared to use low or high tech materials where each was relevant. His interiors are beautiful because he cared deeply about how to illuminate them with daylight, the most precious commodity for an architect, and he wanted people to delight in occupying them and not just find them useful.
His design for the City Tower in Philadelphia, an unbuilt project, showed how radical he could be when he decided to expore structure. This tower, based on a space frame structure in the heady days of Buckminster Fuller, demonstrates that when architects follow an idea through to its logical conclusion it is possible to be both innovative and convincing. Fifty years later, nothing quite like this has been built.

Philadelphia City Tower (unbuilt) A three-dimensional space frame design that would be challenging to construct now, imagine how difficult this would have been in the 1950's.

Philadelphia City Tower (unbuilt) A three-dimensional space frame design that would be challenging to construct now, imagine how difficult this would have been in the 1950’s.

Finally, there is the Hurva Synagogue, and unbuilt project that demonstrates how he could take a design brief and extract a powerful, almost monumental building from it. It has more in common with Egyptian architecture from 3000BC than anything built since then. This apparently simple structure belies the sophistication of the ideas that have gone into it. Seeing it as a model brings home the power of the internal spaces and the imagined quality of the light that would have filtered through the gaps in this powerful structure. Like the Kimball Art Gallery he uses the structure to control the light into thin shafts that would have brought a magical quality to the interior spaces.

I continually find inspiration in Kahn’s work, go along to this and hopefully you will too.

Assessing Microclimate in Urban Environments

“People, life and vitality are the biggest attractions in a city. We see it in the choice of peoples seating, where the most populated benches are located, how people choose to sit on sidewalk cafes facing the people walking by rather than the buildings behind them.
The biggest quality of a sidewalk café is simply the interaction with other people. Do you have a choice between walking through a deserted, empty street and a street with other people walking, people will choose the liveliest street that provides them with more experiences, visual variety and a feeling of safety.” Jan Gehl 2002

This quotation from Jan Gehl, and many others like it, have brought home to the design professions how much we had moved away from a human-centric design philosophy to a building-centric and car-centric design philosophy for much of the 20th Century. Even now we are still living with many of the mistakes made in those decades, a car dominated lifestyle, buildings that don’t address the street, housing with high level access walkways, large highways that unsympathetically cut through historic urban fabric, the list is a long one.

Considering the human impact of buildings and the quality of spaces between them means that we should spend much more time considering, drawing and analysing these spaces than we previously did. The tools are now more available to analyse these spaces than ever before, now we just need to use them more often. Here are some examples of the tools available and where to use them.

1. One can use tools like IES to assess the Wind Microclimate between buildings. The tool uses historic weather data to predict the wind conditions between buildings by calculating how the shape of the buildings that are there already and that are in our proposals will affect the wind speeds throughout the year. This calculation is usually carried out at pedestrian level because that is where the pedestrians are, as well as at higher levels where people might sit on balconies or on roof terraces. The results are compared against the Lawson criteria for pedestrian comfort, a scale that compares the type of activity with the prevailing wind speed. Activities such as sitting outside cafes and window shopping are suggested to be best places where the Beaufort Level 3 ‘Gentle Breeze’ is not exceeded for more than 1% of the time in a simulation. It is a notable failing in the Lawson Criteria that it doesn’t adequately deal with cycling and ‘windiness’. Cycling and wind are are particular problem as this combination presents a risk to life where cyclists can be blown into traffic by sudden gusts of wind, a problem not normally faced by pedestrians. Any suggestions by readers as to what an appropriate criterion would be are welcome.

2. IES can also be used to assess the solar irradiation on roofs to highlight locations for renewable energy systems, helpful in determining whether some buildings overshade others or whether some roofs will get ehough solar insolaton to make it worthwhile putting renewable systems there art all.

3. One can use ENVI-met to carry out a similar assessment, but with the additional sophistication of assessing the impact of planting and street trees on the local environment.

4. We can use ECOTECT to evaluate the solar incidence on the facades of buildings to tell us whether the cafe will be in sunshine for long periods of the year and whether people will get too hot sitting there and whether we should provide an awning. Ecotect is useful for many other type of analysis as well, but its imagery for this type of use is particularly helpful.

5. We can use simple tools like SketchUp to look at shadows cast by our designs at a early stage to assess the impact of one design versus another by comparing the impact at the equinoxes and solstices. This is paricularly helpful as it can be done easily and quickly by the designer in the tool that they are woring on (assuming that they are using SketchUp for early stage designs) and gives them immedate feedback. The other tools used here are for more specialist use and are typically used by consultants who specialise in this type of analysis.

6. There is a substantial piece of work being carried out at MIT to develop a suite of tools for urban design analysis based on the Rhino modelling software. This suite is intended to include tools for early daylight, energy and embodied energy analysis. It is still a work in progress but highlights the level of ambition made possible by readily available computing power. An example of the progress to date is the DAYSIM engine used for modelling daylight in and around buildings.

These are just some examples of the tools available to investigate whether the spaces we are creating between and around our buildings are going to be fit for purpose and enjoyable to use. Here is an example from the Kings Cross masterplan of a very successful intervention, a set of sout-facing steps connecting to the canal. It was popular before the astroturf was added, being a sheltered and sunny place to sit and chat, drink a coffee or eat lunch, now it is both sunny, and more comfortable to sit on.


Sitting in the Sun

Sitting in the Sun: Kings Cross

Housing and Overheating


Dealing with overheating in UK housing and apartment design is quickly working its way up the list of priorities. I still have difficulty believing that DCLG decided to ignore this in the Housing Standards Review, but they did. Despite the Climate Change Committee report on Climate Change Adaptation stating that :

Many homes, hospitals and care homes are already
at risk of overheating. By the 2040s, half of all summers are expected to be as hot, or
hotter, than in 2003 when tens of thousands of people across Europe died prematurely.
A standard or requirement is needed in order to ensure new homes are built to take
account of the health risks of overheating now and in the future. Cost-effective passive
cooling measures should be adopted rather than relying on air conditioning, which will
be expensive and exacerbate the urban heat island effect.

But meanwhile, other, more responsible organisations are ploughing on regardless. The TSB ran a project called Designing for a future Climate and the outputs are here, for anyone interested in the topic, this is essential reading.

The Zero Carbon Hub have just kicked off a project to look at overheating specifically, and will report back early next year.

But what are practitioners to do now? What is a responsible approach?

I propose the following four steps.

1. Don’t use SAP

2. Carry out simulations, and choose the criteria carefully

3. Don’t believe everything simulations tell you

4. People will adapt, make the buildings ready for adaptation

The Detail


Firstly, lets agree that SAP is an inappropriate tool for providing the answer. Overheating will occur in fairly specific circumstances, caused by a complex mixture of factors and may only occur for a specific set of hours in a particular apartment. For example west facing apartments are likely to overheat in the evenings while east facing apartments in the same building may not overheat or overheat at different times of the day,  and the strategy for dealing with the problem is likely to be different from the east side to the west side. Overheating is elevation specific, not plan specific. SAP is not sophisticated enough to tell us when overheating is likely to happen in time, and therefore is unable to point towards useful strategies for dealing with it. There are a number of other tools on the market capable of analysing the problem such as IES and TAS. These are designed for the purpose and are much more appropriate for this use.

Secondly, we should be carrying out simulations on a regular basis of current apartment schemes to assess whether they overheat using current weather as a minimum, and preferably also assessing them with 2050 and 2080 weather predictions.

The standards to use for testing should be adaptive standards such as EN 15251 or CIBSE TM52 for buildings occupied by able and healthy individuals who will adapt to external temperature and who can control their environment, or who can go for a walk in the shade or go to the swimming pool on hot days.

For buildings where the occupants are young or old both of who have difficulty regulating temperature, and who may not be free or able to move to colder places or unable to close shutters, we should use the more risk averse CIBSE Guide A which sets a temperature level that must not be exceeded for a set number of hours per day.

Thirdly, lets agree that simulations are useful and necessary, but again are only guides to likely scenarios and are not facts. Here is a good illustration of the problems caused by taking simulations at face value.

Whilst working on a recent project we were presented with some analysis of overheating carried out by a well known and respected firm of engineers. Among other sensible suggestions they recommended reducing the size of the windows by 50% to reduce the likelihood of overheating by about 1% for the 2050 high emissions scenario. So, to explain, the suggestion was to reduce the area of glazing by 50% because simulations suggested that this reduced the likelihood of temperature in the apartment exceeding an agreed limit by 1% of the time the apartment was likely to be occupied. 1% of the occupied time for an apartment is about 1% of a year, so lets say 3.5 days in total. To reduce discomfort in 2050 for a three day period, the suggestion was to reduce the quality of life for the remaining 18,250 days. We won’t succeed in adapting to climate change by building buildings that no-one likes or wants to live in.

Fourthly, I believe that we will adapt both our behaviour and our ability to deal with warmer climates. The rate of change is slow enough for many species to migrate ahead of changing climate, so why can’t human beings adapt their behaviour too. Wearing different clothes, travelling at different times, closing shutters before going to work, having a siesta are all cheap ways of adapting to warmer climates. All of this makes simulation difficult. A simulation will assume that people in 205o will be cooking using the same equipment that we are using today, and it will assume that the heat gains from cooking will contribute to overheating. It is likely that people will change their cooking habits in warmer summers to avoid cooking at a time of the day when it contributes to overheating, but a simulation run using one of the currently available tools isn’t able to model changes of behaviour and lifestyle over time.

Our buildings need to be designed to accommodate shutters or blinds on the outside of buildings for those parts that are vulnerable to overheating. It may not be necessary to install them now, but it is likely to be necessary in the future, so design them in now. They are a familiar feature to anyone who has been to southern Europe and everyone understands how to use them immediately.

New Housing Quality Standards

There is a lot of discussion and movement currently on the topic of Housing Quality Standards. With the Housing Standards Review a lot of questions were asked by DCLG, but in truth, many of them went unanswered. The cessation of the Code for Sustainable Homes leaves a gap that is not going to be filled by Building Regulations because low carbon housing, even very low carbon housing, is not the same as high quality housing.

With the announcement of the London housing Zones, which will be developed to the mayors Standards, the question must be asked, what the Mayors standards are going to be, if the Code is not to continue?

Most of the issues contained in the Code are not moving to Building Regulations, and the ones that are are not going to be as demanding as the requirements of the Code. My view is that we need more demanding standards than Building Regulations to offer customers choices in the quality of home they want to buy, to encourage innovation in the supply chain, and to point the industry towards future changes in regulation. In the Housing Standards Review, space standards, overheating and daylighting were all mentioned, all of them are important, but none of them are currently regulated. Since the outcome of the HSR there has been a further announcement that ‘minor’ development may not be subject to Building Regulations 2016, and we await further detail.

So we are moving towards a situation where instead of one national standard, we will have two, one for major development and one for minor development, and where local Core Strategies will continue to call for development to meet the Code for Sustainable Homes since it is a very expensive process to change Core Strategies these will remain in place for some time to come. In London we appear to have a different view where the London Plan will remain in place and Code Level 4 will continue to provide a benchmark for new homes, probably because any viability argument against providing sustainable homes would be unconvincing.

The BRE has announced a consultation on the future of sustainability standards, and is suggesting the preparation of a new BREEAM standard for homes which would work in a similar way to other BREEAM standards. The consultation is open until the 25th July and I encourage you to submit a response.

The Housing forum is running a project called Mind The Gap which is trialling the idea of Performance Labelling for Homes. This is using BIM to produce a series of metrics about home performance characteristics, such as space, daylight, energy use, running costs. Could we create a market where house purchasers and tenants compared existing and new homes using the same benchmarks?

My view is that we need a much more ‘consumer’ focussed standard than the Code for Sustainable Homes ever was. The Code never became a part of the house purchasing story, many housebuilders who build Code homes never even attempted to use this as part of their marketing material. The Code was seen as an imposition that added cost but never as a benefit that added value. Any new standard must bridge this gap.

I am on the Technical Advisory Board of ActiveHouse, a pan-European effort to encourage the delivery of homes that are substantially higher quality than normal development but in terms that most home occupiers would understand: warmer, brighter, more spacious, healthier, cheaper to run. These are terms that any purchaser or future tenant can understand and we need to work together to develop a housing industry that speaks about and markets development in those terms, rather than focussing entirely on CO2 emissions which, though vitally important,  are baffling to the majority of people.

This week I spoke about this at the CIH annual conference in Manchester in a Kingspan sponsored event, together with Shelagh Grant of the Housing Forum and Martin Townsend of the BRE. The room agreed that we need standards that go beyond Building Regulations, and my belief is that these standards will only work if we in the industry create them for our customers. I will be hosting a series of workshops at HTA on this topic over the coming months, let me know if you want to be involved.

RIBAJ Sustainability Conference

I attended the RIBAJ Sustainability Conference at ARUP’s in Fitzroy Street on the 24th June and I thought that I would report back on the event.

It was a strong lineup of speakers, most of whom are well known in the sustainability world in the UK, a bit aimed more towards the commercial end of the market than the residential end, but it was all the more interesting for this.

Rab Bennets did a sterling job of chairing the event, including asking knowledgeable and interesting questions when the rest of us had run out of steam.

Lydia Dutton, environmental project manager at Argent, responsible for the environmental targets on the Kings Cross estate, gave us a fascinating insight into the attitudes of a large developer with a long-term view of place making.

Lynne Sullivan of Sustainable By Design talked about zero carbon and what it means, and how we have got to where we are. She compared UK 2016 standards to other EU standards to highlight that although we are making progress, others have either got there before us or are planning to go further than we are. Lynne makes the excellent point that we don’t appear to have a national energy strategy that is meshed with the buildings that we are designing. There is no effort aimed at community energy projects that ties regulation and planning, apart from in London, and even the one in London is not flexible enough to really work.

Richard Francis of Monomoy Company, talked about the productivity benefits of good quality buildings for employers and employees, and how those numbers will dwarf any benefits to be gained from energy savings measures. This seems to me to be at the heart of where the environmental movement needs to go next, to stop counting CO2 beans and to move on to counting benefits and added value.

Adrian Hewitt from Energence Ltd, talked about the difficulties of bean counting CO2 reductions from recent projects, how no one wants to go to the trouble of disclosing the actual numbers. This is preventing us from either gaining the benefits of knowing what is workeing well and what to copy, or what is failing and needs to be improved, with the result that we are probably not achieving the CO2 savings that we think we are as quickly as we need to.

Dr Sebastian MacMillan from the University of Cambridge  talked about how to ensure that we involve people in our projects, that without their involvement and engagement other efforts can easily be wasted.

Paul Scialla CEO of the Well Building Institute talked about the WELL standard, this is a standard that aims to deliver a healthy environemnt for people to work in that is currently being piloted in the US. Some of it sounds startlingly similar to the ActiveHouse Standard, perhaps these people should talk?

Ann Marie Aguilar and Martin Brown talked about the Living Building Challenge.  This is the most ambitious standard in the building industry, and only a handful of buildings in the world have met it. Martin explained that its appeal to him was that buildings that met this challenge were being positive in their environmental impact, providing energy, reusing materials, cleaning water, preventing waste. All of these were going much further than standards that aim to reduce or prevent, this one says that the building must be positive. Ann Marie explained how some of its elements are being explored on the Sky campus.

Chris Twinn of Twinn Sustainability Innovation showed us that if we allow the developing world to adopt LEED Platinum, their energy use will go up, and not down. We shouldn’t be exporting our standards to the developing world, we should be leapfrogging our out-of-date standards to gain the benefits of leaner IT and low energy tablets and LED lighting to cut our services in size, reduce our use of materials and question the models that regulation has given us. Throw away the rules of thumb and the notional building, and calculate the problem from first principles.

Bill Gething then frightened us all by demonstrating how hot it is likely to get in London in the next century, (when all our current buildings will still be in use). In the worst scenarios it could get up to 10 Deg C hotter in London before 2100. We need to design buildings that are resilient to a warmer climate, that can stay cool in those temperatures and that enable people to protect themselves from these impacts.

Polly Turton from ARUP pointed out that sustainability professionals and engineers are stronger together, by working in an integrated way, even between competitors, we can come up with the answers for our clients and for society. I couldn’t agree more.

Housing Zones

The announcement this week of the new Housing Zones is interesting and welcome, but what does it mean for the housing industry? Here is a summary of the proposals.

  • 20 Housing Zones will be created in the capital, aimed at delivering 50,000 new homes
  • Each Housing Zone should deliver at least 1000 homes mostly within the 2015-18 period
  • The Housing Zones will be backed by Mayoral powers to ‘smooth planning’
  • Local Authorities can bid for the zones which will attract funding from a £400m pot
  • 10 Housing Zones will be created elsewhere across the UK with Local Authorities bidding for a £200M pot
  • Bids for funding need to be made available through private sector companies such as developers or RHP’s, not local authorities themselves
  • The deadline for funding bids is the 30th of September 2014

All these Housing Zones will be on brownfield sites, and the funding will be focused on bringing forward schemes that are already well advanced.

Interestingly, given Nick Boles recent letter to Boris, complaining about how different London standards are from National Standards, and that London should get in line,  the announcement includes the following statement…

All new homes in Housing Zones will need to be built to high quality standards, with policy-compliant levels of environmental performance and the Mayor will expect them to conform to the London Housing Design Guide.

Good transport links are deemed a necessity for Housing Zones, either with good infrastructure already in place, or planned, or capable of being brought forward with funding assistance. Most Housing Zones are expected to be in Opportunity Areas

Planning powers such as Planning Performance Agreements, Compulsory Purchase Orders & Local Development Orders will be used to speed up the planning process.

It is anticipated that Private Rental Sector development will form a part of development in Housing Zones, as well as high levels of affordable homes and shared ownership are expected to be delivered. Homes for private sale will be expected to be marketed to London buyers primarily.

A London Housing Bank may assist in providing front funding for new development of sub market rent homes.

It is possible that the Mayor could buy the land using CPO powers and prepare the site for development, offering serviced plots to developers to build out. This is a model used in other European countries to fast track development on large scale brownfield land, such as in Malmo and Hammerby.

All in all this is a positive step and aims to enable London Boroughs to work with the GLA to accelerate the delivery of new housing on sites that can have or already have good transport links. The model has worked elsewhere so one has to wonder why it has taken so long for it to be used here?

It will be interesting to see whether the London Boroughs will follow political lines and work with the Mayor or not, and whether the same London Boroughs will work closely with Developers rather than Housing Associations.

What it does mean is that there will be substantially more development happening in the region in the years 2015-18 than would otherwise be the case, with at least 20,000 units being delivered through this mechanism. With the housing industry already struggling to meet current delivery targets and labour and skills shortages across the sector, there is a lot of work to be done in the background to accelerate training and recruitment across the sector to deliver these requirements.

The prospectus is less clear on the plans for Housing Zones outside London, with a statement that DCLG will publish a prospectus for this later in the year.

Announcement on Zero Carbon Homes in the Queens Speech

Here is the text of the background document to today’s announcement on zero-carbon Homes.

New homes built to a zero carbon standard

The Government is committed to implementing a zero carbon standard for
new homes from 2016. But it is not always technically feasible or cost
effective for house builders to mitigate all emissions on-site.

The Government would set a minimum energy performance standard through
the building regulations. The remainder of the zero carbon target can be met
through cost effective off-site carbon abatement measures – known as
‘allowable solutions’. These provide an optional, cost-effective and flexible
means for house builders to meet the zero carbon homes standard, as an

alternative to increased on-site energy efficiency measures or renewable
energy (such as solar panels). Small sites, which are most commonly
developed by small scale house builders, will be exempt. The definition of a
small site will be consulted on shortly, and set out in regulation.

The Zero Carbon Home standard will be set at Level 5 of the Code for
Sustainable Homes, but the legislation will allow developers to build to Level 4
as long as they offset through the allowable solutions scheme to achieve
Code 5.

(This is a strange piece of text,  the Coalition is using Code Levels to explain an energy compliance scheme. The 2016 standard has almost nothing to do with Code Level 5 and Code Level 4 has very little to do with Building Regulations 2014. Its as though the Code was only an energy standard, and all the other elements didn’t matter so much)

Energy efficiency requirements for homes are set in the Building Regulations
2010 and are made under powers in the Building Act 1984. But there are
insufficient powers in the Building Act to introduce off-site allowable solutions,
so the Government will now bring forward enabling powers for this.


I am assuming that this exemption applies to London, and that anything built within the London Plan zone will continue to meet London Plan requirements irrespective of scale.

The question of what represents ‘small’ is going to be interesting. How small is small?

Thermal Bridging – what’s the value of a y-value

Thermal bridging of construction elements has become a very important part of the compliance of housing in the UK, but you would never know this if you worked for a contractor, developer or architect designing, planning or building the said housing. Despite this being an important factor since 2010, the level of knowledge and understanding in the industry is still very low.

For new readers, thermal bridging is expressed as a ‘y-value’ or amount of heat loss stemming from the aggregated thermal bridges in a design. The thermal bridges occur at every junction in the building, every wall-to-wall connection, wall-to ground connection, wall-to-roof connection, all jambs, cills and heads, and all balconies, projections or bays. Each junction has its own ‘psi-value’ and these are aggregated together to make a ‘y-value’. In order to assess the performance of the building, all the junctions have to be measured and a value assigned to them.

This calculation is carried out using specialised software that calculates the rate of heat movement, or heat flux, through the junction.

To summarise the regulations, there are three options for compliance under UK regulations regarding thermal bridging.

  • take a default value
  • use accredited details or other approved calculations
  • use calculated details where individual junctions are calculated by a SAP or other qualified assessor

The impact of this can be easily illustrated. If we take a typical mid floor apartment, where there is a simple envelope, and two large openings in the façade, one for a bedroom and one for a living room. Where all else is unchanged, the difference between the default value and a calculated value based on accredited details is 0.5% saving of the DER, but when the lintels are changed to a thermally broken type, the saving increases to 3%. If this is the impact on a single mid floor apartment with a very simple envelope, the impact will be greater in a detached dwelling with many more openings.

This demonstrates that changing the manufacturer for a single junction can change the overall performance by 3%. This is the type of change that contractors are used to making on the fly as they make purchasing decisions about the project. They are not used to being tied to a more detailed performance specification that makes such a difference to the compliance of their project.

This lack of knowledge was typified on a project recently where the main contractor substituted one timber frame manufacturer for another, without checking whether the new manufacturer could match the thermal bridging characteristics of the original. The SAP Assessor had used the psi-values of the original manufacturer in the design stage SAP. The replacement manufacturer not meet the specification and they could not supply any information on the thermal bridging of their product at all. They had never been asked for it on previous projects.

This baffles me. Timber frame construction is a naturally thermally efficient construction method, for a company to sell such a system without providing calculated thermal bridging information is to hamstring their own performance for the sake of a few thousand pounds.

The companies who are paying attention to the changes in the regulations are taking the steps to have their psi-values of their products tested in typical constructions and they are using that information to make sales to contractors earlier in the process than usual, bringing themselves into the design conversation at an early stage of the project. By doing so they are getting themselves and their products written into the performance specification for the project. Whether it is thermally broken lintels, high performance windows, better performing insulants, or aerated blockwork, there are a lot of products on the market now which rely on this focus on thermal bridging.

The concern I have is that there is a lot of evidence in the industry that site teams and purchasing teams are not picking up on this need to watch the performance of the envelope, and they are substituting products to save money without paying attention to the psi-values of the materials they are buying. To be fair to them , the design teams need to be more explicit in the information that is provided to them so that it is more obvious to them what products need to be installed to be compliant. It is not reasonable to expect buyers to read through a SAP calculation, so a schedule of psi-values needs to be provided to them with an explanation as to how they were derived and why.

In the long run this focus on the fabric of dwellings can only be a good thing, as this is the best place to find savings in energy that are likely to be sustained in the long term life of the building.


Private Rental Sector – a Naturally Sustainable Approach

In a recent discussion with clients in the PRS sector a number of issues came up for discussion where the private rental market takes a different approach to the speculative housing market and the affordable housing market. These five issues are key to the success or failure of the private rental sector and at the same time seem to me to naturally point towards the design of more sustainable buildings than an equivalent project in the speculative or affordable housing sectors.

1. A PRS landlord is interested in the long term quality of the building: Private rental is a real market, if tenants don’t like it they can leave. Most modern tenancies are short and if the landlord treats people badly, or if a better offer shows up nearby, the tenant will leave. This ensures that PRS landlords will be kept on their toes for the duration of their ownership of the building. The building becomes a live asset, not a sunk cost. This will encourage landlords to maintain their buildings, keep their energy plant well maintained, and to ensure that services are running smoothly. Badly run buildings will lose their tenants more quickly than a well run one. PRS landlords will naturally tend towards better quality design that appeals to the current market. Low energy and high quality buildings will be more attractive to the market.

2. A PRS landlord is interested in the long term performance of the building: The success and failure of private rented buildings at a large scale, is maintaining a margin between operating costs and the rental income. If there is no margin, there is no business. This drives the design of private rented buildings to be efficient in their running and maintenance. The desire to cut out waste is essential to running any sustainable business, so the natural behaviour of PRS management will tend towards a more sustainable business model. The building will be designed to use space efficiently, and to be built with little or no waste.

3. A PRS landlord is interested in the comfort and wellbeing of the resident: Resident comfort and satisfaction will be more important to a PRS landlord than to any other landlord, as this is a key reason for people to stay or to leave. A building that is poorly designed or constructed will have less appeal to residents than a well designed and well constructed one. A building that overheats or is difficult to heat, or where residents can hear their neighbours conversations or music will have a quicker ‘churn’ of tenants. This is more likely to lead landlords who procure a PRS building to ensure that it is well-designed for the residents comfort in the long term.

4. A PRS landlord is interested in the lifecycle cost of the building: The operational cost of a PRS asset will as important to a landlord as its capital cost. In a speculative building the capital cost is everything as the speculative developer has no involvement in the long-term running of the building. This will naturally lead to a more sustainable decision-making process where a balanced discussion can be had as to whether it is better to build using better materials, (in the sense of durability, ease of maintenance,) or whether to use a cheaper material and have to replace it or repair it more often. In a speculative development something that looks good at the beginning is always favoured over something that costs more but will look good in the longer term. It is normal for a PRS client to consider the life-cycle cost of materials and services, and unheard of for a speculative developer to do so.

5. The PRS landlord cares about the long term usefulness and appeal of the building: A PRS landlord has a difficult task as a client to forecast what the market will be like in the future. Will tenants prefer more space, better light, faster broadband? What will future tenants crave that current tenants don’t care about. This means that the PRS landlord must naturally keep an eye on trends for the future rather than living off the trends from the past. A good example is car parking. A speculative developer will insist on including a lot of parking spaces as history says that parking spaces sell homes. In an urban environment this is increasingly not the case, and a PRS landlord will be aware of this and won’t want to take up more valuable space with cars than absolutely necessary.

It is interesting to me that all of these considerations apply to the affordable housing sector too, but because the affordable tenant doesn’t have much choice and rarely wants to leave, these considerations don’t apply as much as one might think. There is a shortage of affordable housing for rent, so the chances of a tenant leaving are less, and tenant concerns are less high up the list of priorities than they could be.

Similarly, the speculative housing sector is dominated by demand, so there is little competition in a specific areas and purchasers have few options. There is no need for speculative developers to consider these issues as the private sale market isn’t working in the interests of the purchaser.

It will be interesting to see how the housing supply chain in the UK rises to the challenge of the institutionally invested private rental building. The standards will be different, the approach will be different, and anyone who approaches it in the same way as a normal speculative housing project will be missing the point, and missing an opportunity to create a long-term, high quality sustainable asset.