The energy-consuming activities carried out in buildings are extremely diverse. Examples spread from boiling water for a cup of tea in the UK and working on a computer in an American bank to using an air conditioner in India or cooking with traditional biomass in Africa. Due to this diversity, there will be no one-size-fits-all solution to decrease energy demand in buildings. Instead, reducing energy demand requires a flurry of solutions to be explored, mixing both technological and behavioural approaches. In a recent study, we analyse the manifold opportunities that buildings offer to reduce energy demand, and compute their potential at the global level.
Reducing demand for space heating and space cooling can take many forms. Improved insulation and the use of efficient air conditioners or heat pumps have the greatest potential to reduce energy consumption for these purposes. Currently, only a small proportion of buildings are properly insulated and the standard materials used to improve building shells are much less efficient than state-of-the-art materials. Similarly with air conditioners and heat pumps: these appliances remain far from their theoretical maximum efficiency. By using best-practice insulation practices and improving the efficiency of heating and cooling technologies, a lot can be achieved. Additionally, by reducing the indoor temperature in cold climates or increasing it in hot climates, energy consumption can significantly fall. Decreasing the demand for floorspace also has an impact, but it remains modest in comparison to the other factors.
Figure 1 The figure shows three scenarios for global energy demand in buildings and their outcome in 2050 and 2100 (grey columns). In the Low and Very Low energy demand scenarios, we assumed ambitious measures to decrease energy demand. The coloured area attributes the reductions to individual actions. The red line shows the level of global demand in 2015.
Hot water plays an important role in our daily tasks, be it for personal hygiene or washing clothes and dishes. By reducing the number and length of showers, our energy requirements can be lowered notably. Hot water needs can also be reduced by using efficient showerheads with a flow of only 2.8 L/min compared to the current US standard of 9.5 L/min. Other ways of reducing hot water needs include using more efficient washing machines and wearing the same clothes more often before washing them.
Overall, we show that energy demand could be halved in the long term by taking advantage of the numerous opportunities to cut down the need for energy in buildings. Because of the ambitious measures assumed in this study, we consider this potential to be close to its maximum.
The future might be bright for energy efficiency in buildings, but there are also important reasons for concern. Some of the measures mentioned above require new technologies to break efficiency thresholds: for instance aerogels or vacuum-insulation panels are very promising materials for insulation, but they are currently at development stage in laboratories. A huge effort in research is needed to bring very efficient technologies onto the markets, and supporting schemes will be necessary to raise their market shares and reduce their costs. Unfortunately, the construction sector is not famous for its propensity to innovate; it is one the most conservative sectors in the economy, investing a very low share of its revenues in research and development. Considering top companies alone, the construction sector spends around 1% of its gross turnover on R&D, only a tenth of what companies in pharmaceutics and information technologies invest.
Changes in behaviours and practices also bear their level of challenges. It is difficult to think of policies that could have a significant and sustainable effect on people’s preferences and habits. For instance, experiments have been conducted to measure the impact of alternative energy bills on electricity consumption, but the effect was modest and not sustained in time. Furthermore, these policies touch on sensitive ethical issues: to what extent should decision-makers try to influence citizens’ preferences?
Despite these caveats, the potential for energy demand reduction is large and concerns many activities carried out in buildings. There is a lot of freedom in the way people arrange their energy practices, combining technologies and behaviours, and individuals as well as policy makers should make use of it.
Levesque A., Pietzcker R. C., Luderer G. (2019), Halving energy demand from buildings: the impact of low consumption practices, Technological Forecasting and Social Change