Modern Building Services

MODERN BUILDING SERVICES NOVEMBER 2021 21 Heat pump products of this type lend themselves to both direct and indirect hydronic circuits, meaning that central circulation loops and secondary return loops are still serviceable. Specific hydronic system design is important, and has developed over years of research to make sure stratification of stored water is maintained to allow the water returning to the Q-ton to be as low as possible. This is important because CO 2 operates at discharge temperatures of around 110°C and high sided pressures of circa 10Mpa. Returning water temperature needs to be as low as possible to accommodate the high energy transfer taking place. Because of this, the system operates with a water ∆t of around 50°C. Using a traditional heat pump system to achieve these leaving water temperatures would require a cascade systemmade up mostly of an air-to-water heat pump and a water-to-water heat pump, increasing capital expenditure and system complexity. Future proof Today’s commercial customers require solutions which offer both high efficiency and low carbon emissions. Improved efficiencies can be achieved through technologies such as two-stage CO 2 compressors that benefit performance at low ambient temperatures and direct energy exchange, meaning WRAS approval is key. This means there is no loss in capacity until -7°C because of vapour injection and remains operational to -25°C, providing hot water all year round and reducing capital costs. The increasing emphasis on low global warming potential (GWP) refrigerants highlights the advantages or products such as CO 2 (R744), which has a GWP of 1 and an Ozone Depletion Potential of 0. As a naturally occurring refrigerant, CO 2 is used as a benchmark when comparing other refrigerants in terms of environmental impact. With products like Q-ton holding the edge in commercial application due to high leaving water temperatures, low GWP refrigerants and the flexibility of a compact modular design, the transition to include space heating application has been the logical next step. With careful design, the accumulated energy can be used as required for heating circuits that maintain low returning water temperatures with simple blending, such as underfloor heating or low temperature radiators, whilst at the same time providing the energy for potable hot water use. FEATURE NET ZERO For more information about Q-ton, visit : www.hrponline.co.uk/prod- ucts/air-conditioning/mhi-air- conditioning/q-ton-co2-com- mercial-hot-water-system/ What is Part 2LA? Building Regulation Part 2LA covers compliance for domestic and non-residential buildings, considering high efficiency alternative sys- tems to improve the energy performance and in turn reduce CO 2 emis- sions. It sets minimum standards of performance of building services equipment and also sets the target emissions rate (TER). Compliance with Part L2A can be calculated using government approved methods such as SBEM (simplified building modelling), SAP (standard assess- ment procedure) and EPC (energy performance certificate). Using SAP10.1 as a reference for g CO 2 /kWh per fuel type, renew- able technologies operating with a COP of 4.3 reduce annual CO 2 emissions by up to 76% compared to electric immersion heaters and 86% compared to gas boilers. What is BREEAM? BREEAM is the leading sustainability assessment method for planning projects, infrastructure and buildings. It recognises and reflects the value in higher performing assets across the built environment lifecycle, from new construction to in-use and refurbishment. It does this through third party certification of the assessment of an asset’s environmental, social and economic sustainability performance, using standards developed by Building Research Establishment (BRE). BREEAM-rated developments are more sustainable environments that enhance the well-being of the people who live and work in them, help protect natural resources and make for more attractive property investments. 2 BREEAMpoints are awarded for using a refrigerant under GWP 10 (CO 2 is <1). 1 BREEAMpoint is awarded for being a hermetically sealed systemwhichminimises the risk of refrigerant leaks.