Energy efficiency programmes (EEPs) are schemes operated by utilities or other bodies in order to incentivize energy efficiency improvement, in particular by adoption of energy-efficient products and typically by means of an economic reward. Ample experience has been gained, especially in the U.S., where EEPs have been in use for decades, with the rationale of avoiding additional energy supply by improving energy efficiency. More recently, EEPs have been implemented in Europe and in Switzerland. This review paper presents insights from the U.S., the EU and especially from Switzerland, with a focus on levelised programme cost of saved energy (LPC) as a key performance indicator. These LPC values, which take the perspective of the programme operator, are typically low to very low compared to the cost of electricity supply, thereby representing an important argument in favour of their use. The country examples show that EEPs are being effectively and successfully put into practice, for example, in Switzerland both as (i) a national tender-based scheme (called ProKilowatt) and in the form of a (ii) utility-operated obligation-based scheme (in Geneva). EEPs not only call for diligent implementation but also for suitable legal settings, e.g., in the form of mandatory energy efficiency savings targets (as realised for energy efficiency obligations, EEOs) in combination with programme cost recovery. The main criticism of EEPs is the free-rider effect, which needs to be minimised. On the other hand, EEPs are accompanied by significant co-benefits (environmental, health-related and social) and spillover effects. In their currently prevalent form, EEPs allow one to effectively save energy at a (very) low cost (“low-hanging fruit”). They can hence play an important role in fostering the energy transition; however, they should be implemented as part of a policy portfolio, in combination with other policy instruments.

Hydraulic balancing is key to ensure proper operation of the heating system. When the heating system is not hydraulically balanced, heat is unevenly distributed across dwellings resulting in a wide temperature spread, overheating, and consequently, wastage of energy. In this paper, we study to which extent hydraulic imbalance affects the thermal energy demand of buildings. Furthermore, key variables and interactions that influence the thermal performance of buildings are identified. In the first part, a dataset, including building features, boiler capacity and energy consumption of 49 multifamily buildings in Geneva (Switzerland), is analysed. Applying regularization regression, we find that higher variation in indoor temperature leads to larger energy consumption. Buildings constructed before 1980, having large boiler capacity and large heated floor area, are more likely to be hydraulically imbalanced and to consume more energy, indicating higher energy saving potential from hydraulic balancing. The second part consists of a case study of four multifamily buildings in Geneva where hydraulic balancing was implemented. We monitor data associated with temperature levels and energy consumption and find that hydraulic balancing significantly reduces the temperature spread avoiding overheating. The yearly energy savings by hydraulic balancing at an outdoor temperature of 0°C are estimated at 9% in Geneva.

Heating systems must be subjected to hydraulic balancing in order to ensure proper operation. When the heating system is hydraulically imbalanced, heat is unevenly distributed across dwellings resulting in a large temperature spread, overheating, and consequently, waste of energy. In this study, we investigate the extent to which hydraulic imbalance affects the thermal energy consumption in buildings. Furthermore, key variables and interactions that influence the thermal performance in buildings are identified. Results show that higher variation in indoor temperature lead to higher energy consumption. Compared to new buildings, old buildings that have large boiler capacity and small heated floor area are more likely to be hydraulically imbalanced and to consume more energy.