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HVAC controls

documented controls strategy

• control strategy documented in the building logbook, to ensure good understanding by building operators (2 - section 6, 1)

Match provision of heating, ventilation & air conditioning to actual demands in the building

• efficient and robust control strategy (matches servicing to occupancy pattern and activity in each zone, and default to off with local override) (2 - section 6, 3)
• servicing of each occupied zone to match its occupancy pattern and activity type (2 - section 06/01/02)
• flexibility to match servicing to varying occupancy levels in a zone e.g. wider temperature control band during cleaning/outside core hours (2 - section 06/01/02)

Adopt an efficient HVAC controls strategy (and zoning) with effective central and occupant controls

• allowance for seasonal variations (2 - section 06/01/03)
• zoning accounting for external/locational factors (e.g. varying daylight levels, external pollution sources, etc.) (2 - section 06/01/02)
• zoning accounting for internal layout/design (e.g. open plan / cellular offices) and use (e.g. offices / halls) (2 - section 6.4)
• appropriate, well designed, local controls (research shows they can improve energy efficiency and reported comfort) (2 - section 6.4)
• sufficient dead-band and zoning on systems with both heating and cooling to avoid cycling and simultaneous heating and cooling (2 - section 06/01/03)
• zone controls so different areas of the building can be heated separately ()
• boiler controls so that the smallest available boiler is used for summer DHW generation ()
• black-bulb thermostats for control of radiant heating systems ()
• two-stage electronic thermostats linked to occupancy sensors in intermittently occupied rooms ()
• 7-day electronic timeswitches to permit different settings for each day and individual settings of ten minutes or less to allow accurate programming for weekend and daily occupancy patterns ()
• extension timer(s) to cope with occasional out-of-hours working ()
• 7-day electronic timeswitches for all electric heaters ()
• electronic two level thermostats with integral run-back timer to switch electric heaters off after a pre-set time ()
• thermostat-controlled de-stratification fan(s) in high-ceilinged rooms to bring warm air down to working levels ()
• humidistat(s) to any extractor fan that is used to remove moist air ()
• optimum start controls, connected to external sensors, on the heating system ()
• thermostatic radiator valves (consider a locking mechanism to prevent unauthorised tampering) ()
• dedicated (central) hot water boiler(s) ()
• smaller supplementary boiler(s) to meet periods of lower demand ()
• condensing (lead) boiler(s) ()
• point of use (gas or electric) water heater(s) for domestic hot water ()
• weather compensator to wet radiator systems (and motorised valve to systems serving floor areas of over 1000m2) ()
• localised radiant heaters controlled by a push button, run-on timer to avoid general space heating where it is not really needed e.g. in atria ()
• longer term options for energy efficiency - replace old boilers, fit thermostats to boilers, insulate boilers and pipework, install efficient double glazing ()
• local heating for small/remote areas (e.g. security offices, controls and equipment rooms) to avoid inefficient use of central systems ()

Reference Documents

	Series Number	Publisher	Title
1	Guide H	CIBSE	Building control systems
2	Guide F	CIBSE	Energy efficiency in buildings
3	TM31	CIBSE	Building log book toolkit

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