Space-saving hot water solution for social tenants in Midlothian

Socially rented flats in Dalkeith have been fitted with Thermino batteries to provide mains pressure hot water for tenants, without the need to use gas. Six new flats were built to Passivhaus standard and four existing flats in the conservation area were retrofitted by facilities management and construction company Morris & Spottiswood on behalf of Midlothian Council.

The challenge

Any hot water system chosen for the development had to meet the requirements of both the newbuild Passivhaus flats, and the existing flats being refurbished. The Passivhaus standard centres around efficiency through insulation and airtightness, which in turn lowers the heating demand of the property.

The newbuild flats are highly insulated with triple-glazed windows and solar PV. Space heating is provided by compact electric skirting radiators, whereas the retrofit properties have electric panel heaters.

The solution

The project design team chose to fit Thermino heat batteries to provide hot water in the newbuild and retrofit flats. Sustainability, lower running costs through lower heat losses, and compatibility with the Passivhaus standard all factored into the decision.

The newbuild flats each have a Thermino 150 ePV, which charges using electricity from the solar PV, while the retrofit flats have a Thermino 150 e using grid electricity.

The benefits

Morris & Spottiswood used Therminos in a previous project for Midlothian Council, this time paired with a gas boiler, showing the versatility of the systems. James McLeish, Site Manager for Morris & Spottiswood said of this project, “The client and the tenant have raved about how much it’s saved on their bills since they’ve moved in.”

Along with lower running costs for tenants, the Therminos are up to 4x smaller than the equivalent hot water cylinder, freeing up valuable storage space in the flats. The tradespeople on site have also benefited from being upskilled in this technology.

James’s advice for other contractors thinking of using Therminos in their projects is to incorporate it into the design at an early stage. He said, “That way you’ve got more fluency coming from the design team, the contractor and the end user, that being the client or tenants.”


“It seems to be the council that’s leading the way with this, but where the council go, you eventually seem to find that private households and housebuilders will follow, and it’ll become more and more mainstream.”

James McLeish, Site Manager, Morris & Spottiswood

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