Water and energy nexus at the building level

‘In recent years, the attention given to the water-energy nexus has grown. Although insight in the energy needed to run our water systems has gained, little is known about the water-energy nexus at the building level, specifically, regarding hot water use. For the Netherlands, total water consumption per capita and residential water consumption is well known, see Figure 1. However, reference to hot water use is often not reported. In 1970, hot water consumption was estimated at 15 litres per person per day (l/pd). Currently it is estimated that a person uses about 60 l/d of hot water of 40° – 60°C, for personal cleaning and kitchen use. Additionally, 13 l/pd of hot water is heated in the washing machine and dishwasher (Blokker et al., 2013). For non-residential buildings, there are no comparable estimates available. Until 2013, the design of the drinking water and hot water system of non-residential buildings was based on outdated assumptions on peak water demand and on unfounded assumptions on hot water demand. In this article we describe the influence of changes in (hot) water use at the building level in the last decades, in the Netherlands. Results show the close interdependency between water and energy over time, and describe an integrated approach towards a more efficient design considering water and energy flows at building level simultaneously.”

(Citaat: Agudelo-Vera, C.M., Blokker, E.J.M., Pieterse-Quirijns, E.J., Scheffer, W. – Water and energy nexus at the building level – REHVA European HVAC Journal (2014)January, p.12-15)