Efficient hot water heating

As homes become better insulated, energy consumption for spatial heating is decreasing. It is therefore increasingly important to have a clear picture of another reason for household energy consumption: hot water heating.

In this project we determined the primary energy demand for hot water heating for a variety of household types. We then developed a method to determine the suitability of hot water heaters on the basis of their energy efficiency, annual energy costs and annual CO₂ emissions.

Extension of the SIMDEUM® model to calculate energy-use bandwidth

We applied SIMDEUM® to six standard household situations to determine the daily primary energy demand for hot water heating under different circumstances (season, hot water temperature, use of shower heat exchangers). In a supplementary step, the model was extended to become SIMDEUM-HW (SIMDEUM Hot Water), which, together with quality declarations of different types of hot water heaters and the NEN7120 standard, establishes the system’s energy efficiency, annual energy costs and annual CO₂ emissions. The new model also takes account of the energy losses that occur during the transport of hot water and the subsequent cooling of the pipes.

Op basis van verbruikspatronen uit SIMDEUM® kunnen voor verschillende standaard woonsituaties de jaarlijkse energiekosten voor de bereiding van warm tapwater berekend worden. A0 staat voor een woning met eenvoudige drinkwaterinstallatie (0) en een huishouden van 1-2 personen (A), D++ staat voor een woning met luxe drinkwaterinstallatie en 3-4 personen. Bron: managementsamenvatting uit rapport

Based on the consumption patterns from SIMDEUM®, the annual energy costs for hot water heating can be calculated for different standard household situations. A0 stands for a household with a simple drinking water installation (0) and 1-2 people (A); D++ stands for a household with a top-quality drinking water installation and 3-4 people.

Model gives installers and consumers insight

On the basis of the consumption patterns from SIMDEUM®, we developed a model that shows how different types of hot water heaters (heat pumps, central-heating boilers, solar boilers) perform in terms of: (1) energy efficiency, (2) annual energy costs and (3) annual CO₂ emissions. The model allows installers and consumers, for a specific household situation, to make a well-founded decision when choosing a hot water heater. It also gives them insight into the impact of energy-saving measures on energy use.

Model studies of standard household situations show that heat pumps, and the combination of a central-heating boiler with a solar boiler, produce the best performances. A shower heat exchanger usually produces an inferior performance, but because of the absolute saving involved, it does nevertheless cut energy costs. The research also indicated that the context in which the energy-saving measures are taken plays a role in the extent of their impact.