Making thick walls are not the only solution for energy efficiency

Energy efficiency approach beyond low U-values (UK vs Japan)

When we think about energy efficiency in buildings, we tend to over-focus on the fabric before anything else. This comes from a ‘fabric first’ approach, which has proved to provide great energy savings and great performance, as demonstrated by the Passivhaus movement. That’s why the UK government has been pushing the construction industry to build with better materials (insulation) as the one and only solution for energy efficiency. However, we might be overlooking other approaches.

A fascinating example is the Japanese housebuilding sector, which is recognised for offering high levels of energy performance for over several years. The sophistication of their machinery and technology is the most distinctive aspect of their building processes, BUT, surprisingly enough, it is not the main reason why their houses are so sustainable.

In Japan, building regulations are very loose regarding the fabric used in their houses. Any building under 300 sqm, does not have to achieve any levels of U-values or air tightness. They can comply with it if they want, but is not mandatory. The way that they ensure that houses consume little energy is by having strict regulations regarding the energy efficiency of the equipment installed in the houses. All mechanical systems, such as boilers, heat pumps, MVHRs, as well as the appliances in the house, like TVs, fridges, electric showers, etc., need to comply with high levels of energy efficiency.

If we think about it, this is a more direct approach to energy efficiency because it focuses on the source of energy consumption, while for a fabric first approach, energy efficiency comes as a consequence of it.

It is important to consider the influence that vernacular construction has in modern Japanese architecture, where houses’ walls were built with paper, and still are! Lose fabric legislations are respecting this tradition and tackling energy efficiency from a different end. Otherwise, how thick would that paper needs to be to achieve Part L U-values?

It does not mean scrapping all progress made to ensure that all our houses are built tight and with good materials. But might be an opportunity to approach energy efficiency from both ends. For example, Passivhaus houses not only need to achieve certain airtightness and fabric conditions, but all the equipment needs to be Passivhaus verified.

Current strategies, such as the Energy Star rate, are designed to persuade the consumer toward energy-efficient equipment but don’t act as regulators. Energy Star might work for self-builders interested in saving some energy or carbon but has little effect on mass housebuilders who are guided by regulations.

In this way, mass builders chose the equipment based on financial reasons. Therefore, it seems common to see them installing the most affordable product in the market as long as it reaches the expected standards or demanded quality. Still, there might be missing an opportunity to make more value from the houses that they sell.

Japanese housebuilders allow customers to select the equipment that they want in their houses. Users can decide on the quality and type of PV panels (tiled panes, high efficiency, coloured, etc.), smart technology, heat pumps, batteries, and so on, from long catalogue lists. They have realised that they can make more revenue by simply installing equipment on demand, as they charge a percentage of the equipment cost. This is what in business is known as ‘added value’.

In order to allow this level of customisation certain aspects of the decision-making process need to be postponed to the sales stages, where customers’ decisions are reflected in the layout of their houses. This is a business strategy, called mass customisation, which can be observed in other industries, such as the automobile or technology sectors. Indeed, Japanese housebuilders deliver high levels of mass customisation and heavy industrialisation.

But, while heavy industrialisation might have a particular relationship with robust production and scale has little to do with customisation or energy efficiency. Japanese achieve high levels of customisation mainly by outsourcing components from other manufacturers, not by investing in the heaviest or fanciest manufacturing machinery. They select to outsource certain components because it allows them to continually expand and update their offer without the need of investing in new machinery, and leave the updating of technology to technology manufacturers.

State-of-the-art machinery in the CSIC Innovation centre in Scotland

In the UK, there is a concurrent discourse stating the need for adopting/implementing new production technologies into the housebuilding process to finally achieve the targeted levels of energy performance. However, the housebuilding industry has been very resistant to implementing industrialised technologies in their construction processes because of the economic risk it involves, considering the precedents of failing ventures that have encouraged housebuilders to blindly block the adoption of any innovative process. And probably they are right.

Independent builders interested in building dwellings with high energy performance in the UK are currently capable of getting a wide range of mechanical systems and construction components (which might, or not, be produced in the UK) enough to build a house up-to-the Japanese or Passivhaus standards.

(Sekisui house and Urban splash house configurator)

The UK housing sector could adopt the added-value production model observed in the Japanese context to increase the levels of energy efficiency by increasing the customisation offered in the housing market. It means allowing house buyers to choose their mechanical systems and renewables to their own criteria.

UK housebuilders might be interested in adopting this model as it implies significantly lower economic risks than investing in heavy machinery. The implementation of an added-value model requires a deep understanding of the existing market and effective communication with the suppliers to coordinate production chains with design and selling processes.