Glossary
Commercial HVAC, translated into plain English.
Every term we use on quotes, reports and site visits — VRV, TM44, F-Gas, SFG20, SEER — defined the way an engineer would explain it, not the way a spec sheet does.
Categories
Category
Equipment
- VRV / VRFVariable refrigerant volume/flow multi-zone systems.
- VRV (Daikin) and VRF (all other manufacturers) describe the same technology: one outdoor condenser serving many indoor units on a single refrigerant loop, with each zone independently heating or cooling. VRV/VRF is the default choice for offices, retail chains and hotels above roughly 30 kW of load.
- Split systemOne indoor unit paired to one outdoor unit.
- A split air conditioner pairs a single indoor evaporator to a single outdoor condenser via a refrigerant pipe run. Single-splits suit small server rooms, individual offices and shops up to about 12 kW. Multi-splits share one condenser between 2–5 indoor units.
- ChillerWater-based central cooling plant.
- A chiller cools water (typically to 6–12 °C) that is pumped to fan coil units, air-handling coils or process loads across a building. Air-cooled and water-cooled variants exist. Chillers are the norm on larger commercial and industrial estates above 200 kW.
- Heat pumpReversible refrigerant plant that heats and cools.
- A heat pump moves heat rather than generating it, delivering 3–4 kW of heating for every 1 kW of electricity in typical UK winter conditions. Modern VRV, split and monobloc air-source heat pumps are the primary route for decarbonising commercial heating.
- AHU (Air Handling Unit)Central plant that conditions and distributes air.
- An AHU filters, heats, cools, humidifies and moves ventilation air through ducted supply and extract runs. AHUs sit at the centre of most fresh-air, mixed-mode and 100% outside-air ventilation designs — commonly with chilled/heated water coils fed by a chiller or heat pump.
Category
Compliance & regulation
- TM44Statutory 5-yearly AC energy inspection.
- TM44 is the CIBSE-authored, government-mandated air conditioning energy inspection required for every non-domestic building with combined cooling capacity above 12 kW. Inspections must be lodged every five years by an accredited assessor. AccuTemp is TM44-accredited and lodges reports on the national register.
- F-Gas RegulationUK rules on fluorinated refrigerants.
- The F-Gas Regulation controls the use, handling, leak-testing and disposal of fluorinated refrigerants such as R32, R410A and R454B. Any company handling more than 3 kg of refrigerant must be F-Gas registered, and every engineer must hold a personal F-Gas certificate. AccuTemp is F-Gas company registered.
- REFCOMUK F-Gas certification scheme for contractors.
- REFCOM is the UK's largest F-Gas certification body, auditing refrigerant handling procedures against BS EN 378 and the F-Gas Regulation. REFCOM registration is the accepted evidence of competent refrigerant work for landlords, insurers and PQQ prequalification. AccuTemp is REFCOM registered.
- Constructionline GoldTop tier of the UK's main procurement PQQ.
- Constructionline Gold is the highest verified tier of the UK's most widely used procurement prequalification, evidencing financial stability, insurance, health & safety and quality management. Fewer than 100 HVAC firms hold it. AccuTemp is Constructionline Gold verified.
- SFG20Industry standard for planned maintenance tasks.
- SFG20 is the BESA-published standard schedule of maintenance tasks and frequencies for building services, referenced by most FM contracts and landlord PPM specifications. AccuTemp's PPM contracts map every visit to the relevant SFG20 task lines.
- PPM (Planned Preventative Maintenance)Scheduled maintenance to prevent failures.
- PPM is the routine, scheduled servicing regime — filter cleans, refrigerant checks, F-Gas leak tests, electrical inspections and photo reports — that prevents unplanned failures and extends equipment life. AccuTemp offers 6- and 12-month PPM contracts starting from £100 + VAT per visit.
Category
Refrigerant
- R32 refrigerantLow-GWP refrigerant used in modern splits and VRV.
- R32 is a single-component HFC refrigerant with a global warming potential (GWP) of 675 — roughly a third of the legacy R410A it replaces. R32 is now standard across Daikin, Mitsubishi Electric, Fujitsu and Toshiba split and VRV ranges sold in the UK.
- GWP (Global Warming Potential)How much heat a refrigerant traps vs CO₂.
- GWP measures how much heat a refrigerant traps in the atmosphere relative to the same mass of CO₂ over 100 years. F-Gas quotas restrict the total GWP of refrigerant placed on the UK market, driving the transition from R410A (GWP 2088) to R32 (675) and R454B (466).
Category
Performance
- SEER / SCOPSeasonal cooling and heating efficiency ratings.
- SEER (Seasonal Energy Efficiency Ratio) and SCOP (Seasonal Coefficient of Performance) are the EU/UK seasonal efficiency figures for cooling and heating respectively — measured across a full operating year rather than at a single design point. Modern R32 splits typically achieve SEER >7.0 and SCOP >4.6.
- kW (cooling capacity)Rate of heat removal in kilowatts.
- Cooling capacity is quoted in kilowatts of heat removed at nominal conditions (return air 27 °C dry-bulb, outside 35 °C). A rule-of-thumb office load is roughly 100–150 W/m² depending on glazing, occupancy and IT — a 100 m² sales floor typically needs 10–15 kW of cooling.
Category
Controls
- BMS (Building Management System)Central controls for HVAC, lighting and metering.
- A BMS is the head-end control platform that sequences HVAC plant, monitors alarms, logs metering and enforces schedules. Modern BMS platforms (Trend, Tridium Niagara, Schneider EBO) expose data via BACnet or Modbus — the same interfaces AccuTemp's predictive controls sit on top of.
- Predictive HVAC controlSelf-adapting AI layer above the BMS.
- Predictive control uses self-adapting AI to learn how a building actually responds to weather, occupancy and internal loads, then pre-empts demand rather than reacting to setpoints. AccuTemp Solutions' predictive layer typically cuts HVAC energy up to 25% and operational carbon up to 40% without replacing plant.
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