SPONSOR CPD PROGRAMME Air source monobloc heat pumps for refurbishment applications This module explores the application of single-stage air source vapour compression monobloc heat pumps, particularly alongside gas-fired boilers, in existing buildings In the UK, and elsewhere around the world, there are significant incentives for owners and operators of institutional and commercial buildings aimed at encouraging the adoption of heat pumps in new and refurbishment projects. This CPD will focus on the application of simple, single-stage air source vapour compression monobloc heat pumps, particularly where they are employed in conjunction with an existing (or new) gas-fired boiler to meet year-round heating demands in existing buildings in order to reduce operational environmental impact. The growing demand for the installation of heat pumps is driven by environmental requirements and financial considerations in terms of both lower operational costs and subsidised, or grant-aided, capital cost and installation. In existing buildings, financial assistance is typically provided to upgrade existing heating plant and, in recent years, several UK government incentives have focused on educational and other institutional facilities. Many such buildings are decades, or centuries, old and use high-temperature narrow delta T systems, often designed to the historic low temperature hot water (LTHW) 82C flow, 71C return water temperatures that are now considered archaic, as well as wasteful of resources in both capital and operational terms. The current widely employed and commonly available simple heat pump technologies cannot reach those temperatures effectively; the thermodynamics of the vapour compression cycle and the properties of many of the commonly employed synthetic refrigerants make it impossible or at least inefficient to do so. Many heat pumps also require a narrower temperature difference across the condenser (which is used to heat the returning LTHW) than the historic 82/71 systems were designed for. There are a variety of solutions available that can effectively produce higher temperatures and, in some cases, operate with wider temperature differences Continuing professional development (CPD) is the regular maintenance, improvement and broadening of your knowledge and skills, to maintain professional competence. It is a requirement of CIBSE and other professional bodies. This Journal CPD programme can be used to meet your CPD requirements. Study the module and answer the questions on the final page. Each successfully completed module is equivalent to 1.5 hours of CPD. Modules are also available at www.cibsejournal.com/cpd across the condenser. These include highpressure, transcritical CO2 systems, ammonia and hydrocarbon (HC) systems, bivalent systems (which typically include a gas boiler, as well as a heat pump), and cascaded refrigerant cycles. As noted in Heat pump retrofit in London,1 before any systems are designed or installed it is preferable to maximise the energy efficiency of the building. Aside from the direct benefit of reducing the overall demand for heating, this will reduce the capital investment required for the heat pump systems, reduce the required LTHW flow temperatures, and potentially improve the useful building thermal capacity in order to store heat that can provide benefits from time-shifting peak loads. The guidance explains that, compared with gas boilers, heat pumps require a more detailed and accurate understanding of the heating and cooling demand. Oversized heat pumps can suffer from lower efficiencies, so correct sizing is essential for efficient operation that meets the buildings needs. This requires appropriate investigation, preferably from contemporaneous records or measurements of the thermal loads. Among the comprehensive and accessible coverage of heat pumps the recently published and freely downloadable CIBSE AM17 Heat pump installations for www.cibsejournal.com August 2023 47