Is London going to go Zero Carbon?

Business Green reported an interchange last week between the Mayor and Green Assembly Member Darren Johnson  in response to his question about the Mayors position on Zero Carbon homes. Boris’s reported response was

“What we are looking at is making sure that we can continue, through the London Plan, to ensure that Zero Carbon Homes are delivered in London and we will be issuing further guidance in due course to provide industry with the certainty it needs about how to do that.” 

Boris reported that London aims to achieve a 60% reduction in CO2 by 2025 and has achieved 14% to date. This represents a per capita reduction of 20% as London’s population has grown by 600k during the reporting period.

It is heartening to hear these words from the Mayor, and I hope that the candidates for the Mayoralty are listening. If devolution is to mean anything it should promote the ability of cities in the UK to sidestep the damaging and short-sighted environmental policies of central government.

Having recently completed a large zero carbon scheme at Hanham Hall with low-rise construction and learned what it means for most of the UK’s housing development, I thought that it would be useful to share below some analysis that we have done to assess how tall buildings can achieve the zero carbon standard. Given that many of the buildings that are proposed for the capital in future are going to be tall it is interesting to assess how the regulations might affect those building types.

The analysis has been done for a twenty five and a forty storey tower with six units per floor to demonstrate how different systems meet the targets. We tested gas boilers, CHP with gas backup, all-electric heating and hot water and finally Air Source Heat Pumps. Three of the four rely on a communal hot water distribution system, the all electric system being the exception.

Energy Options to meet the London Plan and Zero Carbon

Energy Options for a 25 Storey Tower to meet the London Plan and Zero Carbon



Energy Options fora 40 Storey Tower to meet the London Plan and Zero Carbon

What the research shows is that for taller towers there is no difficulty in meeting the current definition of zero carbon. In fact it shows that achieving it is technically easier than achieving the London Plan, as the London Plan has a lower emissions target than the Zero Carbon definition. This is assuming that there is no special treatment for electric heating or hot water, unlike the current version of SAP which is based on comparative performance rather than on a definite figure as set out in the Zero Carbon Hub’s definition.

Based on these figures I would say that towers should be forced to meet the lower emissions target of 10kg/CO2/sqm since in both gas-based options this target can be met. Perhaps an all-electric version could be left as it is at the higher 14kg/CO2/sqm.

It also shows that a very efficient 25-storey building can meet the targets irrespective of the energy system used, the top graphs shows that it can achieve the target in all four options, even an all-electric option. The 40-storey is not so easy. My assumption is that only the roof can be used to house renewable energy,  but for the 40-storey version it would be necessary in the electric options to put some pv panels on the facade to reach the target.

But of course the technical success is not the full picture. In addition to the Fabric Energy Efficiency target of 39kwh/sqm/yr that apartments have to hit, and towers have no difficulty doing so, there is the Carbon Compliance which is shown in the graphs above, and again there doesn’t appear to be much of a problem for towers, but finally there is the Allowable Solutions element which says that whatever CO2 emissions remain must be offset. This offset is achieved by multiplying the tonnes of CO2 emitted, by the figure of 30 years, and by an agreed sum for each tonne. Currently the GLA uses £60/tonne. This produces a figure of approximately £1,000 per apartment to offset the emissions elsewhere.

Sadly the all electric system is unwelcome in London as it it not seen as ‘futureproof’ according to the gas-led ideology preferred by the GLA. This is understandable as an all-electric system does not emit the lowest CO2 emissions possible, at current levels of grid CO2 intensity. What will be interesting to see is how long before the grid CO2 intensity drops to a low enough level to change that thinking. The Committee for Climate Change has suggested that we need to stop burning gas by 2035 to meet our carbon budgets. What is the point in investing in gas burning equipment and networks now if they have to be decommissioned in less than twenty years time?

Certainly an all-electric system is the cheapest to install, avoiding the central distribution system, and it could be argued that an all electric system is just as futureproof as a hot water led system as the Grid is inherently flexible. Interestingly our research also suggests that in the majority of cases an all-electric system is cheaper than a communal system for residents as the standing charges are lower, even if the energy bills are higher than gas. The standing charge is used to create a sinking fund to replace the communal system. If there is no communal system the sinking fund is either not needed or is much smaller, thus lowering residents total bill. The cheapest system of all to run is an individual gas boiler, but no-one would consider installing that into a tower, and it has a higher maintenance and replacement cost than an all-electric system.

A major hole in this analysis is that it is carried out using SAP, which is pretty poor at dealing with apartment buildings. The energy for pumping heat around the building is ignored, as is the energy for ventilating corridors, pumping hot water, lifts, communal lighting etc, etc. Since the communal spaces in these buildings are not heated, SBEM isn’t particularly useful either. As buildings get taller these additional energy uses and losses will become more a more significant part of their energy use, we need better tools to assess them, and more regulations to deal with their particular demands.


VELUX Daylight Symposium 2015

The Location: The event was held at the Tobacco Dock, a reminder that some reused buildings provide stunning locations for events, and in this particular case the event was held in daylight. It may sound obvious, but most conferences are still held in locations where daylight is excluded, in case it interferes with the presentations. The usual result is a lot of sleepy attendees watching a lot of fairly tedious slides. When light levels are lowered, our bodies natural inclination is to go to sleep, a fact that the designers of most auditoria seem to have ignored. 
The lantern lights of this tremendous building were modified by simple banner-like screens to prevent glare and the two days were spent with the delegates bathed in full daylight but still able to view the screens. I cannot emphasise enough how much nicer an experience it is to spend a day in this way, rather than buried in the bowels of some convention centre.


The Content: The Daylight Symposium is a unique event, bringing together the worlds leading experts in daylight research and practice. It happens every two years and brings together the authors of CEN standards, the authors of daylight calculation software, the research community working on the effects of daylight on productivity and well-being, and the authors of guidance on the provision of daylight in design. There were also a few architects like me who tried to keep up with the science and not make fools of ourselves by asking really stupid questions, like, ‘what is the difference between lumens and luminance?’*

Some Conclusions

Over the two days I listend to a diverse range of speakers, from all over the world, many technical, some beautiful, all of them interesting. There were some particular highlights for me.

Daylight Autonomy, The CEN Daylight Standard draft appears to signal that the time has come to move on from Daylight Factor as a means of measuring daylight in architecture. Daylight Factor is a simple metric that predicts the amount of daylight in a room expressed as a percentage of the daylight available from an overcast sky. There are several problems with this.

Daylight Factor is not comprehensible to most people, including many professionals. It doesn’t relate either to the location of the space being examined or to the likely weather conditions in that location. So a room of the same size will achieve the same results in Iceland as in Uganda, despite the available daylight being quite different in the two locations. It doesn’t take into account the availability of greater amounts of daylight and sunshine available under typical weather conditions, so a part of the country where there is routinely a lot of sunshine will appear to perform as well as an area that has much less sunshine. As overheating becomes more of a problem, this is counterproductive. 

The CEN recommendation, based on several presentations during the event, is that we move to a measurement based on the availability of light in the room for a proportion of the day. This is similar to Daylight Autonomy, the US standard used in the LEED sustainable buildings assessment method. The draft CEN standard will suggest that we use a measure of the light levels in lux in the room expressed as the time that a desired light level is exceeded in a proportion of the space. The example given as a minimum is 300 lux in 50% of the room for 50% of the time. 300 lux is enough light to read, write or carry out office work, so it is adequate for many activities likely to be carried out at home. 50% of the space allow for variations in the lighting, particularly spaces only lit from one side. 50% of the time allows for variations over the day, so a room that is well lit in the morning can still comply with the requirement, as well as a room that is well lit in the afternoon, or early evening.

The draft CEN standard suggests that there could be three levels of such a standard, a minimum, set at 300 lux, a good at 500 lux and a high at 750 lux.

Rendering with Daylight: A particular bugbear of mine is architectural rendering that shows interiors bathed with light, when in fact such light is either impossible or unlikely at best. This doesn’t do anyone any good. Architectural rendering has a purpose, but that purpose should not be to mislead the designer or the client. It was heartening to see a presentation of Keyshot, a photorealistic lighting tool that can interface quickly with the VELUX Daylight Visualiser. They are both written by Luxion and they are now capable of interacting with each other. The VELUX tool can check the daylight in the room and Keyshot can produce a verifiably accurate daylight render. It can also deal with materials,textures and artificial light, but the important point is that it renders daylight accurately so that designers can check what actual difference their design changes make to the spaces rather than being fooled by a rendering engine that allow the designer free rein with the amount of light available. (In case you think that software doesn’t mislead, and I am overstating the point, one well-known and widely used rendering tool allows the designer to make the sun bigger!)

Thought Provoking: Paul Bogard: The organisers, VELUX, like to intersperse the hard science with some thought provoking speakers, and this time there were two presentations, one at the end of each day. The first by Paul Bogard was not about daylight, but about darkness. His book, The End of Night concerns the fact that most children in developed countries have no idea what a starry sky looks like. I was lucky enough to grow up in a rural area where starry skies were often visible, and the full majesty of the universe could be felt by anyone coming outdoors after dark. Today there are few places in the Western world where this is possible without having to get into a car and drive long distances. Will we end up in a world where fewer children want to become astronomers because they are unaware of the possibilities, or fewer philosophers because they haven’t seen how small and insignificant we are in the grand scheme of things. Paul points out that much of the problem is caused by security concerns and homeowners and property owners being sold lighting systems that waste a lot of light, and don’t even provide good security.

Thought Provoking: Olafur Eliasson: The presentation at the end of the second day was by Olafur Eliasson an Icelandic artist who, among other works, has filled the Tate turbine hall with a sun, and put large chunks of Arctic ice outside a hall where one of the COP talks was taking place. Bizzarely, one of the delegates contacted him a year later to ask him to bring the ice to the next COP. He had to tell the delegate that sadly, the ice had melted, but that there was more available in the Arctic.

He presented his kickstarter project with Little Sun which aims to bring artificial light to countries where children currently cannot read or study after dark unless they use kerosene lamps. His talk was deeply contemplative, almost mystical. His use of language was amazing, given that he works in Berlin and was born in Iceland, so must use at least three languages every day to express the most complex of thoughts. Two thoughts that stayed with me are:

The Shaping of the world is the creative act, and not the work itself.

Cultural institutions allow people to share without agreeing.
* ‘Lumen is the total luminous flux emitted by a light source, and luminance is the amount of light emitted from a surface in a particulat direction’ Obviously!

The Triumph of the City – Edward Glaeser – A Review

Edward Glaeser has penned this work on the benefits of the city from the perspective of the economist.  A useful and unusual perspective, the first major work on cities  from an economics perspective since Jane Jacobs penned ‘The Death and Life of Great American Cities’ and ‘Cities and the Wealth of Nations’. 

The book is wide in scope and exhaustively annotated, and suitable for use as a textbook as well as being an interesting read. Every town planner and every city councillor should be forced to read it and not allowed to make a single plan or decision without  reading it.

Glaeser is not such a good writer as Jacobs, but he does create some pithy one-liners that could go on a city planners or mayors annual calendar.

The essential ingredient for the success of the modern city is the accessibility of talent. The basic premise of the book revolves around this statement.

Cities and Talent

Glaeser writes extensively on the subject of cities abilities to attract talent, including presenting many case studies of city growth and city failure around the globe over the last two centuries.

When presented with a series of trade-offs including the cost of housing, the ability to earn high wages and the potential to be close to good schools, families will make a decision to go to the city or suburb that gives them the best likelihood of success. Cities that cannot provide all three are likely to be limiting their ability to attract the greatest amount of talent.

He points out the particular problem of enabling and maintaining good schools in inner cities and although this is heavily US-centric there are relevant comparisons to be made in the UK, particularly in London where there are fewer good schools in inner city areas and many families move to the suburbs in search of good schools.

Glaeser points to many examples of cities that have used good education systems, particularly universities, such as London, Paris, Boston to keep their best and brightest people and to attract outsiders: ‘to thrive, cities must attract smart people and enable them to work collaboratively’ and ‘Because the essential characteristic of humanity is to learn from each other, cities make us more human’

He points out, rather romantically for an economist, that the advent of the connected society through cyberspace has in no way lessened the neccessity of face-to-face connections with talent. ‘connecting in cyberspace will never be the same as sharing a meal, a smile or a kiss’

The Sustainable City

He makes the point that were China and India to live the way the US does, and follow a path of abandoning the inner city for the ‘exurbs’, would raise the planets CO2 emissions by 139%. He suggests that there is some evidence that the Chinese ‘get’ density in their deign of places. Whether there is evidence that the Chinese ‘get’ quality of life in the same way, I am less sure. But his central point is well made, we can only offer convincing advice to developing countries if we are seen to be busy repairing the damage we have done ourselves already. The US has some way to go on this point.  ‘The only way the West can earn any moral authority on global warming is to first get its own house in order.’

Being an economist, and having dealt with the improvements that many cities have made to their transport systems through congestion charging, he points out that ‘Unless we charge people for the carbon they emit, they won’t emit less’.

He suggests that the exurbs are a temporary phenomenon and limited to some places, rather than having a general future. But he doesn’t have the evidence to back this up. ‘I suspect, that in the long run, the twentieth century fling with suburban living will look, just like the brief age of the industrial city, more like an aberration than a trend.’

Misguided Conservation

He makes a strong point about misguided conservation in places like California. (it could easily be London) where he points out that Environmental Impact Assessments (EIA) only assess the impact of develoment being built, and not the impact of it being built elsewhere instead; which is unfortunate because elsewhere in the US is a place like Houston where there is less development control than in California and where more houses are being built, and which are therefore cheaper and more attractive to workers and familes. But the result is a higher overall carbon footprint because Houston is uninhabitable without air-conditioning. And everyone drives everywhere. Conservation in California keeps California the way the rich Californians like it, but means that alternative places which are less suitable for sustainable living are used instead. In the UK, substitute Surrey for California and the result is largely the same.

He maintains that people who fight dense development in order to protect local low density life or green spaces  are simply moving the problem elsewhere, an elsewhere that is further from services and transport infrastructure that will mean more develoment on green field sites and more car travel.

‘The interests of people who oppose change are certainly comprehensible, but their interests usually don’t match the public interest.’

Policy should aim to encourage development in those parts of the country where it makes most sense, near to infrastructure and jobs, and not on creating areas of land like Green Belts that have little or no real environmental benefit but which results in more sprawl further away from economic centres and longer commutes for workers who cannot afford urban prices. ‘Urban living is sustainable sustainability,rural ecotowns are not.’ 

It seems to me that the difference between the UK and the US is that the results of long commutes is less obviously harmful in carbon terms as our cars are more efficient and public transport networks are good, but if you look at Charles Montgomery’s book on Happy Cities, you will see that the costs of long commutes include broken marriages and unhappy children because of the absence of one or both parents for most of the day. Environmental reasons are not the only reasons to be concerned by the need for long commutes.

On Urban Poverty

He takes a seemingly rather cold hearted look at urban poverty and points out that ‘Cities will always have poor people, and this is a sign of success, not failure, as cities should attract poor people who want to improve their lot’. Certianly the history of London and New York bears this out as places where waves of immigrants have come, found places to live near to the ports, worked in these cities, gradually become part of society and then moved from the enclaves where they started out together for mutual suport and eventually merged with society as a whole. There is a building in the East End of London that has been a mosque, a synagogue, and a church at different times as different cultures arrived and left.

‘Cities especially benefit from an influx of talent, because immigrants help urban areas play their crucial role of connecting countries.’

He deals well with the economic benifits of collecting talent in the same location, both for cultural movements and technical innovation. The problem is when cities create areas of poor people who will always be poor, as has happened in many areas of the UK where social housing has been built in large clusters. Sometimes this has resulted in creating communities where unemployment and benefit dependency has become a way of life and difficult to disrupt. He pours scorn on efforts in many US cities where attempts at regeneration have focussed on building infrastructure and housing in failing places where neither were needed, and suggests that a better use of money would have been to give it to the disadvanteged and allowed them to move to wherever they would prefer to live. A chilling piece of evidence that he provides is that poorer children displaced from New Orleans have demonstrated improvements in school results in the communities they have moved to. Sometimes, he suggests, new buildings are not what is needed.

On Management

‘The more centralised a nations government, the larger its capital city, because people are attracted to power as ants are to picnics’

‘Much of the world suffers under awful governments, and that provides an edge for those cities that are administered well’ He doesn’t examine the different types of civic government that have worked well, but its interesting that the examples he cites tend to be places where a strong individual took control, often for a sustained period. The same can be said of the failures.

‘..among cities, failure seem similar, while success seem unique’

Glaeser identifies a common problem of political and cultural attitudes to city life, which has often found its way into city management in the past, and still does today. Political animals who must attract votes from the wider community don’t always understand the particular needs of the cities under their control, or even how to ensure that they are managed properly. The conflict between what is good for the country, and what is good for the city is dealt with through a number of case studies. His comments about the negative impacts of taxation could have been written about the UK.

‘Cities can compete on a level playing field, but over the past sixty years America’s policies have slanted the field steeply against them. In the areas of housing, social services, education, transportation, the environment and even income taxes, American policies have worked against urban areas. Cities have managed to survive despite these advantages because they have so much to offer.’

When it comes to managing a city budget, he is unequivocal:

‘As much as I appreciate urban culture, aesthetic interventions can never substitute for the urban basics.‘ These are Safety, Education & Transport.

His case study on Singapore is very interesting as it demonstrates how a city-state can function without a rural hinterland. ‘Singapore’s success illustrates the irrelevance of acreage’. Again, he makes the point, as Jane Jacobs did, that cities are really the economic engines of a modern society, and as they need resources it doesn’t appear to affect their success or failure where those resoures come from. Provided the city can attract and keep talent, and maintain a good economic strength, it can afford to buy the resources that it needs. He fails to point out that the resources also come with a carbon footprint and outsourcing production of resources, such as food, from long distances, has the same effect on CO2 emissions as curtailing developent within its boundaries.


If you are interested in urban design, sustainability, town and city planning, then this book should be on a shelf close to your desk, alongside the works of Jane Jacobs and Henry Montgomery.

Zero Carbon London

I attended a roundtable hosted by the NLA last week on Zero Carbon housing in London. The purpose was to discuss the issues around zero carbon, whether the current definition is appropriate in London, and how to develop policy in this area. The event was well attended by housing consultants, with the NLA, Zero Carbon Hub and DCLG represented.

It was interesting to hear that little analysis has been done to date on the impact of the new definition of Zero Carbon on housing projects over four stories. The current definition is aimed primarily at the housebuilder market who mainly develop suburban sites, rather than on developers who bring denser urban sites to market. DCLG and the ZCH acknowledged that there is a piece of work to do on assessing medium and high-rise dwellings.

The likelihood is that the Fabric Energy Efficiency Standard will not be difficult for higher rise buildings because of the inherent efficiencies in building more dense developments. But achieving Carbon Compliance will be much more difficult because the use of PV as a proxy for CO2 reductions will not work in this context. The ratio of roof to floorspace won’t be high enough.

There was a lot of discussion about the potential for district heating schemes to fill this gap, some were in favour, and some against. There was some realism from the engineers present, acknowledging that some district heating schemes have an efficiency of only 30%. This may be caused by poor design and implementation, and would change dramatically as such systems proliferate. But the problem is that there is no sign that these systems will proliferate, they are simply too expensive in capital terms to be viable in the current market.

The alternative which was discussed at length, is the upgrading of the existing housing stock. In London there is a huge backlog of poorly performing dwellings that need energy efficiency upgrades and the Allowable Solutions monies coming from new development in London could be pooled to fund these upgrades. A likely figure for the monies available is £1500 per new dwelling after 2016, and if London achieves a target of 30,000 units per year, this could deliver £45M of annual funding. This could pay for 4,500 external wall insulation retrofits per year.

While it may be chickenfeed in the context of the Green Deal it is still worth doing, and worth delivering guaranteed emission savings, immediately. That is worth having.