Delivering efficient heat

Dimplex, heat pump, electric heating, space heating
Heating and hot water for this student residential block, which has a ‘Very good’ BREEAM rating is provided by a mixture high-temperature air-source heat pumps and tightly controlled electric panel heaters.

With building managers under increasing pressure from the Government to perform in line with the UK’s green agenda, the close management of carbon emissions and onsite energy consumption is quickly becoming a priority. Karen Trewick of Dimplex explores the latest heating technologies available to help organisations optimise their energy efficiency and cut their heating costs.

Heat-pump technology is not a new concept to the commercial sector. There are thousands of installations delivering low-cost, low carbon heating for offices, schools, hospitals and more — helping buildings to meet required levels of efficiency and contributing significantly to high BREEAM scores for those buildings with additional sustainability targets.

Although the initial capital cost of installing a heat-pump system can seem off-putting at first to organisations compared to oil or LPG boilers, for example, when specifying heating systems for commercial buildings it is important to consider the long-term benefit of reduced running costs.

The Government’s non-domestic Renewable Heat Incentive (RHI) was launched in 2011 and offers financial incentives, specifically guaranteed tariffs over 20 years, to switch to certain green technologies. Ground-source heat pumps were included from the birth of the scheme, but it is not until recent changes were made that the non-domestic RHI has really opened doors for the commercial building sector.

In May 2014, air-source heat pumps were included in the scheme for the first time with a tariff of 2.5 p/kWh. At the same time, the tariffs for renewable heat generated by ground-source heat pumps were also increased, with split tariffs of 8.7 p/kWh for the first 1314 h of operation and 2.6 p/kWh for any operation over 1314 h.

For the healthcare and education sectors in particular, the need for energy efficiency is combined with stringent guidelines on the safety of heating appliances.

NHS Estates guidance notes state that the surface temperature of space heating appliances such as convectors and radiators should be controlled to prevent burn incidents, recommending a maximum surface temperature 43°C. And with no specific guidelines for the education sector, schools and nurseries will inevitably seek the same stringent levels as the healthcare sector.

Low-surface-temperature (LST) heat emitters prove to be the standout option for both healthcare facilities and schools, when specifying heating appliances to meet the NHS best practice guidelines. One variation is using a fan boost to accelerate the hot air from the heater and reach a room temperature of 20°C more quickly. The other benefit of a fan convector is that the heater can be made more compact than appliances of comparable output but without a fan.

Electric heaters also take away the need to consider the position and temperature of surface-mounted pipework for a centrally heated system (that which is positioned within 2 m of the floor), which would need to be securely insulated and boxed-in if carrying water above 43°C to conventional radiators.

It is understandable that many businesses remain cautious when confronted with the need to find budget for substantial investment in new technologies. However, now is the time to invest in energy-saving products and reap the benefits.

Dimplex, heat pump, electric heating, space heating
Supported by the Renewable Heat Incentive, heat-pump technology is a cost-effective approach to meeting heating and hot-water requirements.

An example of an actual installation is the heating and hot-water system for the new student residences development next to the £81 million new campus at University of the West of Scotland at Ayr.

Achieving the ‘Very good’ BREEAM rating, the industry-leading standard for best practice in sustainable buildings, the development is at one of the UK’s most modern, environmentally-friendly and sustainable higher education learning establishments, with a campus design inspired by the area’s woodland surroundings.

The university’s new £7 million student residences building accommodates nearly 200 students and has four Dimplex 26 kW high-temperature air-source heat pumps working with Dimplex electric panel heaters to meet the space-heating and hot water requirements.

The accommodation for the students is arranged as large, en-suite bedrooms and studio flats in clusters, with spacious kitchen and lounge areas. Space heating is provided by Dimplex EPX panel heaters.

The building has high levels of insulation with low air-permeability levels. These panel heaters have with highly sensitive thermostats and fast warm, enabling the required eco standards to be met.

The university also wanted a simple and straightforward heating system that not only needed to meet a demanding capital cost budget but also provide efficient running costs longer term. The Dimplex solution allowed them to achieve all this and added in extra control of the all-inclusive student energy costs by adding in PX controllers and press-button delay timers so heat is only provided when the units are occupied.

Karen Trewick is director of communications with Dimplex.

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