Tom Wallace - Building Technology - ECO



Since the Paris Climate talks, it seems the world is at last waking up to the issues of Climate Change and the associated problems of global warming and sea level rise. Our prospects, I think, have improved somewhat over the last few years. But there is still a lot to do. In any case, because of the time lag in the influence of greenhouse gases in the atmosphere and how temperature rises will affect the oceans, we have perhaps another 40 years during which things will continue to get worse and before we can hope to see the results of any improvements made now becoming apparent in our climate. You can check the statistics for Carbon Dioxide and other factors on this website:-

Architects and other construction professionals have tried to do their bit by looking to make buildings more energy efficient and using materials that are more environmentally friendly. Legislation has also been toughened considerably in order to address the energy issue in particular. All of this of course is well-intentioned and is to be welcomed. But there are problems in looking at just buildings or energy use in isolation, without also looking at the broader issues of sustainability. In this section of the website I want to look at some ecological proposals relating to buildings, but also consider some wider concerns. For buildings, I consider if a new building is always the best solution. Also considered is the size of buildings, renewable energy, insulation and ‘breathability’. In looking at the broader issues of sustainability I will also consider lifestyle choices that can have a much greater impact on the planet and therefore put our architectural choices into some sort of context.

Rebuilding and Renovation

Replacing buildings is a slow process. One report at least has suggested that without a wholesale rebuilding programme energy targets will not be met. However, it depends of course on what exactly is put in place of the buildings that might be considered for replacement. Even on the question of energy use it has to be pointed out that at least one third of new buildings in the UK fail to meet the energy standards that in theory they were designed to achieve. Then add to this the size and space required. For low-rise developments, new houses often require two parking spaces to be provided - sometimes with space for cars to turn on site - along with about 170 square metres of garden ground. For flats and high-rise, there are still parking requirements and amenity land and drying areas required. For commercial developments, often one parking space is required per occupant. Then there is the infrastructure needed to get all these vehicles to these new buildings. Planners might regard all this as an ‘improvement’, but in sustainability terms, all of the extra infrastructure needed by new buildings more than offsets the energy savings gained by the more efficient buildings. Providing so much by way of roads tends to just encourage car use. Meanwhile, many of the streets and towns that are often regarded as desirable in aesthetic terms have a much smaller scale and require a slower pace to navigate through them. There is a failure on both the aesthetic front and the energy equation when older higher-density designs are swept away in favour of car-centred suburban sprawl. As such, I would suggest - RENOVATION IS ALMOST ALWAYS BETTER THAN REBUILDING OR NEW BUILD.

Renewable Energy

Renewable energy for houses and other buildings usually refers to ‘micro-renewables’, that is , small scale energy installations that serve the needs of the building directly. Examples would be solar panels, a wind-turbine or a micro-hydro installation. For the individual, this at least makes economic sense. Micro-renewables, along with other features such as insulation, triple glazing and more efficient heating systems will sooner or later offset their original installation cost and save the householder or business owner money.

At the time of writing (2017) it looks as if the world is on the brink of a large scale move toward electric vehicles. As such, the electricity demands of the nation are about to increase very significantly. At the same time, the cost of large-scale renewable energy installations is starting to compete favourably with fossil fuels and nuclear. It might be that the grid can cope with the extra demands, at least in terms of the total amount of energy required. However, some back-up of storage of power - perhaps shared between battery storage in houses and electric car batteries - may be beneficial to smoothing out peak demands that the grid may struggle to meet. The grid is already being adapted to cope with many much smaller scale inputs of power and will need considerably more adaptation in the years ahead.

Sometimes the reason for adopting micro-renewables is because power from the grid is mostly produced by way of fossil fuels or nuclear power. This is increasingly not the case. As the grid becomes greener, the arguments for micro-renewable are changing. There is still going to be a cost saving of course as there will be less energy to buy from the grid. Perhaps the other argument will be energy security - having sufficient power stored in houses and other buildings to be able to charge up vehicles and cope with any power cuts that may result from a much more variable energy supply.

A brief summary of micro-renewables follows and I would be happy to provide more details for specific types on request.

By far the best option for most households is an air or ground-source heat pump. This takes heat from the ground or air and uses it to heat water - often as part of an underfloor heating system. Such a system will use about a third of the electricity than if the same amount of heat were delivered directly. With the grid being increasingly green anyway, it makes for a very eco-friendly solution.

Solar panels are another good option. These come in two main types, solar photovoltaic (PV) to generate electricity and solar thermal to heat water. Solar PV panels are often used to feed power back to the grid, with a payment made to the householder. They can also be used to generate power for storage in batteries. It will probably be a few years yet before this stored power can be directly shared with electric cars, but that would seem to be the way things are heading.

Along with the feed-in tariffs for solar PV, there are tariffs available for all types of renewable energy sources as well as grants available for the initial installation costs. You can find out more about the current funding options via the Energy Saving Trust website, here:-

Wind turbines, biomass boilers and small hydro-electric schemes are generally more suitable for slightly larger projects. Please get in touch if you would like more information about these options.


The levels of insulation required for a new-build property or for an extension are now almost as high as can reasonably be achieved. There is still plenty of scope though for retro-fitting to existing buildings. The main concern for insulation - both in new build and existing situations - is condensation. The greater the temperature difference between the inside and outside of a building and the more sealed in terms of air-tightness, then the greater the risk that condensation may occur somewhere within the structure of the building. As such, it is always good to get someone to check the condensation risk involved in whatever insulation solution is proposed. The most common cause of condensation problems is a lack of adequate ventilation towards the cold side of the insulation. That is why little vents are added to existing roofs for instance, or small vents added across the surface of new walls. Cavity fill insulation can therefore be particularly problematic, since obviously this is filling in the air space that would otherwise be helping to minimise condensation risks. It is much better to line cavity walls internally and retain the cavity, but of course this means a lot more disruption to the property.

As to insulation products themselves, there are a lot of options. All commercially produced insulation carries a code that is supposed to indicate its impact on the environment (GWP - Global Warming Potential, with a value of zero being best, five as worst.) Products made from sheep’s wool, hemp, wood or recycled paper or clothing are more eco-friendly solutions. Buildign materials such as cobb, straw bale and earth-bunded walls and turf roofs all have good insulation properties.

The more eco-friendly insulation products are often used within a so-called ‘breathable’ construction, described below.

Ventilation and Breathable Construction

Ventilation and condensation risk have been touched on briefly in the preceding section. Obviously all buildings need to have a flow of fresh air and there are regulations about how this is provided. Basically the ideal is to avoid ‘unintentional’ air flow (drafts) and to carefully control ‘intentional’ air flow (ventilation). The latter is normally done by means of small vents to the tops of windows and doors and also by providing extract fans to kitchens and bathrooms. There can also be mechanical means of providing all of the ventilation to a dwelling or other building, with heat recovered from the outgoing (and therefore warm) exhaust air. (This is known as Mechanical Ventilation with Heat Recovery - MVHR.)

The amount of ventilation provided has a bearing on heat loss. The more ventilation then the more heating (or cooling) is required to keep the building at a constant temperature. In calculations for new buildings, this is factored in. There is also a requirement to test for air-tightness of the completed building prior to final documentation being prepared.

Breathable structures are often heavily promoted by fans of eco-architecture. I am therefore including a description here, but have to say that I am somewhat sceptical about the benefits - as I will explain. Breathability has much more to do with water vapour (and therefore control of condensation) than with actual air flow, so it is important to be clear that it is not specifically about ventilation. Certain materials allow for the passage of water vapour better than others, and it tends to be the more natural, and therefore often the eco-friendly materials - that provide the best breathability. The theory is that this is a healthier and potentially better means of managing condensation risk within structures than the use of constructions that rely on vapour barriers. The same calculations used for more conventional constructions can be applied to breathable constructions, and there is usually no problem having them accepted for the purposes of Building Standards. (I am less sure about straw bale and cob constructions - which are also breathable in theory, but often have no clear cavities within the construction build-up. In my experience, councils usually look for a clear ventilated cavity, usually to the back of the weathered external surface of the building element.)

I have used breathable constructions in several projects without any problems. However, in areas of high exposure and heavy rainfall, care must be taken over the large amounts of moisture that can get into walls in particular. The moisture will need to find heat to allow it to evaporate, and this heat will inevitably come from inside the building. So, whilst the construction will certainly get rid of the moisture and avoid condensation, it will result in a loss of heat. A less breathable construction will not have this problem. Unfortunately the issue does not show up in normal heat loss calculations, where heat loss due to evaporation is not considered.

Context and Lifestyle

Building a new eco-home or retro-fitting an existing building with micro-renewables and insulation is a good thing so far as it goes. But it is also important to see this within the context of where the building is situated and also within the context of more general lifestyle choices.

Planning legislation makes a sharp distinction between development within a town boundary and development in the countryside. (See ‘Consents’ and ‘Finding a Home’ pages for more details.) Wales has publicised its Planning policies regarding eco-homes in the countryside quite widely. Scotland has similar concessions for rural eco-homes. Such homes may be accepted where more conventional designs would not. The main criteria for acceptance is that the property makes full use of its surroundings in order to function. For instance, it may use a river to generate power via a micro-hydro installation, perhaps have a ground-source heat pump and the owners may grow willow as a secondary fuel source and also grow their own food. However the impact of any new build property must be kept in mind, especially when it is on a greenfield site. The lifestyle of the owners will have a big impact on whether or not such a design is likely to be a success in environmental terms.

As such, new or retro-fitted buildings within a town or city will generally perform better than rural developments. For one thing, a city will often be three or four degrees warmer than the countryside, which in a cooler climate is a distinct advantage during most of the year. Also it means that services such as gas, electricity, telecoms, water supply and sewerage are likely to be close by. For larger developments in particular, surface water drainage (from roofs, parking areas and roads) can become a major cost. Turf roofs and soft landscape features can help ease the pressure on the surrounding drainage network and reduce flood risk as well as encourage wildlife. For the building occupants, there is likely to be less travel involved with a town-based development that one that is more rural.

Apart from the home or building itself, travel and food are other lifestyle factors that have a major impact on the environment. Despite giving a cautious welcome to electric vehicles, the infrastructure needed for all the travelling done in developed nations is still immense. The move towards vegetarian and vegan diets is only partly about animal welfare. The world cannot sustain the whole population eating meat for instance without diverting land away from growing cereal and vegetable crops. There is just not enough space to achieve this. Where our food comes from and the impact of all stages of food production is a major concern.


Many people love the countryside and the seashore. Even in these crowded islands there are still relatively unspoilt places that can be visited and appreciated for their beauty. Little by little though, another field or woodland or stretch of coast gets swallowed up for ‘development’ and a bit more beauty is lost along with a bit more bio-diversity. Along with this there is a little less resilience left against the problems of climate change. Sometimes it seems there is nothing individuals can do because the problems seem too big. But the problem is as much about the little patch of woodland or other wild place in the local area as it is about world issues. Each person has the opportunity to look at their own small circle of influence. Lots of smaller actions at the personal level can add up to a big change.

Perhaps an ecologically sound lifestyle can seem to be about all the things that we have to be sacrificed in order to achieve sustainability. But it can also be seen as a shift from a fast-paced consumption-orientated lifestyle to one that is quieter, slower-paced and more focused on local economies and harmony with nature. In these terms, it can be about abundance rather than just sustainability. But it is an abundance that involves different sorts of pleasures to the ones offered by consumer capitalism.

I am more than happy to discuss all of these issues with clients. In particular, I would encourage self-builders and co-housing groups to get in touch. There is a lot that can be done outwith conventional building techniques, and this often suits the self-builder in particular. Meanwhile, community projects offer the opportunity for high-density housing solutions and shared facilities, all of which can provide savings in the use of energy and materials. Further information is available on all matters discussed on this page.

The average UK citizen is responsible for around ten tonnes of CO2 per year. To meet the UK's climate change targets, this needs to be reduced to two tonnes by 2050 and reductions need to be happening already. To check progress, please visit:-

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