This guide provides detailed guidance for the installation of fixed building services in new and existing dwellings to help compliance with the energy efficiency requirements of the Building Regulations. The guide covers the design, installation and commissioning of:* Conventional means of providing primary and secondary space heating, domestic hot water, mechanical ventilation, comfort cooling and internal and external lighting.* Low carbon generation of heat by pumps, solar thermal panels, and micro-combined heat and power systems. The guide sets out recommended minimum energy efficiency standards for components of building services systems, including the use of controls. For systems installed in new dwellings, the standards are design limits (or backstop values). For new or replacement systems and components installed in existing dwellings, the standards represent reasonable provision for complying with the Building Regulations. Changes to the 2018 edition The 2018 amendments to the guidance come into effect on 6 April 2018 and the key changes are as follows:* A new, higher efficiency standard for replacement gas-fired boilers in dwellings.* A requirement to install time and temperature control for all gas and oil-fired boiler installations, including replacement boilers.* A requirement, when replacing a gas-fired combination boiler to install at least one energy-efficiency measure from the following list:o flue gas heat recovery systems o weather compensation o load compensation o smart controls with automation and optimisation functions Contents Introduction * Gas-fired space and water heating * Oil-fired space and water heating * Electric heating * Solid fuel heating * Community heating * Underfloor heating * Mechanical ventilation * Heat pumps * Comfort cooling * Solar water heating * Lighting * Micro-combined heat and power * Heating system circulators * Abbreviations