This scheme, developed by SDC Construction and designed by Thompson Cole Architects for North Hertfordshire Homes is providing 60 homes with mixed property types and tenures of a contemporary design built to be environmentally sustainable while still reflecting the original design principles of the Garden City. The houses and flats are arranged around ‘home zones’ and a central park. The construction value of the development is approximately £8 million.

The development has many environmentally friendly features. The heating system for the 18 private houses incorporates Nu-Heat’s solar thermal for hot water and for the 42 social housing apartments Nu-Heat has designed and supplied an integrated system comprising underfloor heating, air source heat pumps and solar thermal controlled via a series of building management systems. This specification meets the CfSH Level 4.

Nu-Heat’s original brief was to design systems based around ground source heat pumps, but the cost of drilling boreholes in this instance was prohibitive. Nu-Heat provided energy data to the developers for the alternative of air source heat pumps enabling assurances to be given that Level 4 would still be met.

In total there are nine Stiebel 12kW ASHP serving four/five apartments each. These heat pumps were originally chosen as they could be sited internally (along with their high output, excellent CoP even at low outside temperatures and efficient defrosting) but the decision was taken later to site them externally according to the 9 communal stairwells.

The plant rooms are located under the stairs and house the buffer tanks, pumps and building management system (BMS). What makes this project special is the inclusion of the BMS. As ASHP can only work efficiently if they have been set up correctly, the need for any interaction between the tenants and the hardware has been removed, meaning that the only controls they have access to are similar to those of a boiler system. The BMS, which includes heat metering and heat pump performance, is being linked back to Nu-Heat’s offices for monitoring purposes. Nu-Heat has previously installed BMS in a number of smaller projects with great success.

The roofs are green in two ways: environmentally and aesthetically! Their design incorporates sedum roofs that absorb rainwater, minimizing extra discharge into the drainage system (enhanced additionally by a rainwater harvesting system), and includes zinc-seamed pods at a south facing angle that give the perfect tilt for the solar thermal as well as providing light into the kitchens located immediately below.

Nu-Heat Registered Installers Steve Bradford of Renu Heat and Matthew Saunders of Eco-Energy were tasked with the installation of the UFH, ASHP and solar thermal systems along with the building management systems. The two teams are working in tandem on separate sections of the site to ensure that the installation keeps pace with what is a very fast build.

Project Images (click to enlarge)