CPD PROGRAMME | HEATING, COOLING AND VENTILATION main fabric elements including walls, roof elements, floors and windows, as shown in Table 1 have been reduced by around a quarter compared with the previous requirements. The targets set by the notional building for a project will depend on the size and use of the building, and the systems installed, which will combine to deliver the TER for a building that has improved energy performance. The fabric minimum standards are intended as a back stop, and the TER and TPER will be met by a combination of: Fabric energy efficiency Efficient building services Low- and zero-carbon technologies. Before construction commences on a new building, an analysis is required of the technical, environmental and economic feasibility of using high-efficiency alternative systems. Example systems are noted as: Decentralised energy supply systems based on energy from renewable sources Cogeneration District or block heating or cooling, particularly where it is based entirely or partially on energy from renewable sources Heat pumps. The building specification can change during construction, but the completed building must still meet the targets. When construction is complete, the calculations for primary energy and emission rate must include any changes made during construction, as well as using the measured building air permeability. ADL2 requires that controls for comfort cooling and air conditioning systems should meet BS EN 152323 Energy performance of buildings impact of building automation, controls and building management class C or above. Class C is a standard building automation and control system (BACS) and is essentially environmental zone control for temperature and ventilation. For space heating or air conditioning systems with an effective rated output greater than 180kW, the control system is required to: Fully comply with BS EN ISO 164844 Building automation and control systems Continuously monitor, log, analyse and allow for adjusting energy use Benchmark the buildings energy efficiency and inform the person responsible for the facilities or building management about opportunities for energy-efficiency improvement Allow communication with connected fixed building services and other appliances in the building, and be 56 August 2022 www.cibsejournal.com Limiting U-value W.m-2K-1 or air permeability Element type Previously ADL2 2021 Roof (flat roof) 0.25 0.18 Roof (pitched roof) 0.25 0.16 Wall 0.35 0.26 Floor 0.25 0.18 Swimming pool basin 0.25 0.25 Windows in buildings similar to dwellings 2.2 1.6 All other windows, roof windows, curtain walling 2.2 1.6 Rooflights 2.2 2.2 Pedestrian doors (including glazed doors) 2.2 1.6 Vehicle access and similar large doors 1.5 1.3 High-usage entrance doors 3.5 3 3.5 10 m3.h-1.m-2 8m3.h-1.m-2 Roof ventilators (including smoke vents) Air permeability (for new buildings) @ 50Pa 3 Table 1: Minimum performance standards for fabric elements (Source: ADL2A 2013 and ADL2 2021) Type Packaged air conditioners single-duct type EER SEER NDBSCG 2013 ADL2 2021 2.6 3.0 Packaged air conditioners other types 2.6 3.0 Split and multi-split air conditioners >12kW 2.6 5.0 Split and multi-split air conditioners 12kW SCOP D rating 5.0 Variable refrigerant flow/variable refrigerant volume (VRF/VRV) systems, including room unit 2.6* 5.0 Water-to-water chillers <400kW 3.9 5.0 4.7** 6.0 Water-to-water chillers 4001,500kW Water-to-water chillers 1,500kW 4.7 6.5 Vapour compression cycle chillers, air-cooled <400kW 2.55 4.0 Vapour compression cycle chillers, air-cooled 400kW 2.65** 4.5 0.7 EER 0.7 1 1.6 Absorption cycle chillers Gas-engine-driven variable refrigerant flow * not including room unit ** >750kW Table 2: Minimum efficiency standards for comfort cooling (Source: Non-Domestic Building Services Compliance Guide: 2013 Edition and ADL2 2021) interoperable with fixed building services across different types of proprietary technologies, devices and manufacturers. ADL2 notes that a BS EN 15232 Class A-rated-type system would meet these requirements. For existing buildings, consequential improvements are required, in a similar way to earlier regulations, for buildings with a floor area greater than 1,000m2 when a space is extended or a new/extended building service system is installed. This would require coincident energy efficiency improvements to the building where they are technically, functionally and economically feasible. ADL2 section 12 on consequential improvements is rather easier to follow than the appendix in the previous ADL2B. ADL2 Table D1 highlights the acceptable energy-efficiency measures that should usually be installed when consequential improvements are required. This includes broadly similar requirements to the previous AD, including upgrading heating systems, cooling systems or air handling systems that are more than 15 years old, by providing new plant or improved controls. ADL2 also includes some important changes to requirements for building services equipment specifically, how energy efficiencies are measured and demonstrated. The requirements for comfort cooling equipment must now