Renewable and zero emissions heating systems in affordable housing projects: evaluation

An evaluation of renewable and zero emissions heating systems in 21 Scottish affordable housing projects. This study assesses the estimated, actual, and counterfactual costs of the projects’ heating systems and determines the drivers behind decision making.

List of definitions


For the purposes of this study, capital expenditure (capex) is defined as the equipment and installation costs of a heat and hot water generation and storage system.

District heat network

A district heat network is a communal heat system to which heat is provided by a single source, such as a biomass boiler or ground-source heat array, to multiple buildings via underground insulated hot water pipes.

Heat pump

A heat pump is a device that moves heat from an environment (atmospheric air, the ground, or a water source) and uses electricity to raise its temperature to provide space heating and hot water.

Heat battery

A heat battery is a thermal store that uses a phase-change (liquid to solid material) to store hot water.


A Low and Zero Carbon Generating Technology (LZCGT) is defined by the Scottish Government as one of the following technologies: wind turbines, water turbines, heat pumps (all varieties), solar thermal panels, photovoltaic panels, combined heat and power units (fired by low emission sources), fuel cells, biomass boilers/stoves and biogas.


The Standard Assessment Procedure (SAP) is a methodology implemented by the UK Government that uses information relating to the design of a home and climate and occupancy assumptions to determine if the energy and environmental performance of a new home meets building standards

Section 75

Under Section 75 of the Town and Country Planning (Scotland) Act 1997, a large housing development may be obligated to include affordable housing in order to receive planning permission. Therefore, the affordable housing portion of the development is sometimes referred to as its 'Section 75 requirement'. Opex For the purposes of this study, operational expenditure (opex) is defined as the fuel or electricity costs associated with running a heating system (and excludes maintenance costs).



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