Control of DHW storage charging

What is DHW-1b?

DHW-1b is a smart-ready service within the Smart Readiness Indicator (SRI). The SRI measures how well a building manages smart technology, divided across nine domains.

This service focuses on the Domestic Hot Water domain. It concerns the control of domestic hot water storage charging, that is, the moment when a storage tank is refilled with hot water.

DHW-1b counts towards both method A and method B of the SRI assessment. Method A is the simpler variant, covering 27 of the 54 smart-ready services.

What functionality levels are there?

The SRI defines functionality levels from 0 to 4 for each service. DHW-1b has three levels defined.

• Level 0: No functionality present.
• Level 1: Domestic hot water storage tanks are present, without smart control.
• Level 2: Automatic charging control based on local renewable energy availability, or based on electricity grid information. This is also called demand response or demand side management (DSM), adjusting energy use to match grid supply.

A higher level means the building can actively respond when solar or wind energy is abundant, or when the electricity grid requests it.

Why does this service count towards the score?

Each smart-ready service is assessed against seven impact criteria, such as energy efficiency and grid flexibility. DHW-1b contributes especially to flexibility, because hot water charging can be shifted to favourable moments.

The final SRI score of a building is expressed as a percentage and placed in one of seven classes, from below 20 percent to 90 to 100 percent.