[70] Efficiency in use

The many attempts to define ‘nZEB’ all come up with a list of stand-alone requirements, such as a well-insulated and airtight building shell, efficient HVAC system and a high share of renewable energy. Never mentioned is how to connect them. The EPBD 2018 recast, with its improved focus on controls and automation, could fix the broken chain in the building codes [62, 115].

Any remaining missing links? How about a lifecycle dimension: nearly zero-energy on a spreadsheet is still far from real and persistent performance [124]. Let’s not build policies on the sandy grounds of predicted savings but make user-centric thinking the driver for continuous improvement – even when the building changes function.

[57] Energy transition and circular economy

Green manufacturing is not only about decarbonizing industry’s energy system. It is equally about using sustainable material flows that are at least carbon-neutral.

Reducing waste and recycling materials have to play a major role. But with increasingly complex, miniaturised products using multiple, composite materials, material recovery results in new challenges. Examples of such products are personal electronic devices, batteries, solar panels etc.

Low carbon material streams are likely to become one of the major remaining challenges in an 80-95% greenhouse gas reduction scenario.

[56] Investing in trains or stations?

Where to focus when aiming for an energy efficient subway system: stations or trains? The Warsaw metro did both, investing in energy efficient trains as well as in highly efficient lighting in the stations.

But probably the best efficiency measure is to make public transport more attractive, comfortable and secure – even if such efforts would increase energy consumption of stations. It could stimulate travellers to take the subway instead of other, less efficient means of transport. And it could improve the occupancy rate of the trains, which has a direct positive influence on system efficiency.

[52] Raising the bar

In 2012, the American Council for an Energy-Efficient Economy (ACEEE) investigated the energy efficiency programs for utility customers in the US. The low hanging fruit had been harvested and the bar had been raised, so what can be done to keep energy efficiency savings rolling in?

Part of the answer comes from the ever more efficient technology that is available on the market. Just as important is to better focus customer segments in order to increase participation in energy efficiency programs, and to achieve a better understanding of customer behaviour and motivation.

But the biggest energy savings could come eventually from a systems approach to provide integrated energy services.

[45] No silver bullet

Households display three types of behaviour to reduce energy use. Curtailment involves repetitive efforts such as switching off lights, fans and other appliances. Maintenance refers to practices to ensure appliances and equipment are in good running condition. Buying more efficiently means purchasing energy-efficient products and services.

Curtailment behaviours are most common, but savings derived from them are often grossly overestimated. Energy savings from buying more expensive but more energy-efficient appliances are frequently underestimated. The opportunities to save energy through good maintenance interventions also merit much more attention.