Heat Pumps Today

25 By Biatur Mandia, Renewable Project Heating Engineer at Cor-energy CIBSE YEN NW Chair With the current heating decarbonisation dilemma, Biatur claims that engineers/ consultants should fully explore heat pumps before moving to a gas heating system. This article shows a short case study when using heat pump and gas boiler. It also outlines a procedure to design heat pumps for heating and hot water in existing stock. Introduction The electric grid has improved the carbon factors considerably in the past years; for this reason, using electricity to heat buildings is seen as carbon friendly option. Heat pumps go far beyond this and use electricity to run the thermodynamic process that captures low-grade heat from the air/ground/water and delivers it at a high temperature to the building. This process enables incredible carbon savings while improving the e ciency of a “common” gas system by at least three times. Heat pumps should always be the first option when mindful of energy and carbon. The capital cost of a heat pump is generally higher than a gas heating system; however, several green schemes are currently in place to reduce the costs. Significant grants exist to install heat pumps, the domestic sector with the Boiler Upgrade Scheme, the Public Sector with the PSDS, and the commercial sector with various Green Heat Network opportunities. A heat pump can also reduce the running cost of a “common” gas heating system, and more importantly, it scales down any future price increase. With the above in mind and the changes in the Building Regulations and EPC in favour of heat pumps, heat pumps will gradually become the primary source of heat in the UK. Short Case Study The case study considers a care home built in the 80s. The energy and carbon emission of two heating systems were calculated using IES VE. The heat pump shows massive improvements in both carbon and energy; this also reflects in the EPC of the building. Info www.cor-energy.co.uk www.acrjournal.uk/heat-pumps Heat pump for existing buildings T R A I N I N G Building Type Healthcare Building Area 712 m 2 Location Leeds Lighting LED CIBSE heat loss 75.7 kW Heat pump Gas Boiler Carbon emission System Electric 13,645kg 354kg Carbon Emission System Natural Gas 0kg 71,730kg Total Carbon emission of the system 13,645kg 72,084kg Annual Electricity consumed by system 95.1MWh 2.5 MWh Annual Natural gas consumed by system 0 MWh 341.3 MWh Annual Total Energy consumed by system 95.1 MWh 343.8 MWh EPC (Only for Illustration) A (20) D (76) Heat pump design process for Retrofit The lack of knowledge in the heating industry is delaying the implementation of heat pumps. This section outlines a procedure to design heat pumps for heating and hot water in existing stock. Conclusion Engineers/Consultants should fully explore heat pump systems before moving to a gas heating system. The benefits of heat pumps are not limited to carbon emission, but also include energy, EPC, present & future running costs and proof technology. Improving heat loss, Hot water flow outlets, and heat recovery will reduce the heating demand. In retrofits, it is also important to reduce the electric consumption by implementing LED, efficient equipment, and PV. 1 Reduce Energy Demand The approach consists of extrapolating CIBSE estimations for the input data and use industry-standard software to calculate the demand and peak profile. Temperature can be measured and tested. Efforts should be focused on reducing the temperature. 2 Establish Demand and Temperature There are several types of heat pumps depending on the heat source, refrigerant, and temperature. It is recommended to involve suppliers at the early stage of the design. 3 Selecting the technology The heat pump is sized based on energy demand, technology, and level of centralisation. In retrofits hot water and space heating should be separated when possible. 4 Sizing the HP Building Considerations such as plant space, location, noise, and vibration can con- strain the size of the heat pump. If this is the case, step 6 can reduce the size; if not, re-iteration from step 1 might be necessary. 5 Building Considerations The system can be optimised using controllers and BMS. Storage tanks and control strategy can reduce the size of the heat pump and improve its stability. 6 System Optimisation Re-iteration