Rules of thumb - space and weight allowances | Archive Titles

Table 1: Floor space allowance for services (as a percentage of floor area)
Design area	Application	Other information	Rule of thumb
All services	Simple factory	听	4%
听	Offices and commercial	听	6-10%
听	Hi-tech building	听	15-30%
Air conditioning (excluding boilers and refrigeration)	Fan coil system	听	1路5-2路5%
听	VAV system	听	3-4路5%
Cooling towers and air-cooled condensers	听	听	0.3-1路5%
Electrical services (excluding sub-stations and standby generation sets)	听	听	0路5-1路5%
Lift motor rooms	听	听	0路2-0路5%
Refrigeration (excluding cooling towers)	Central plant	听	1-2%
Ventilation	Toilet extract	听	0.3-1路0%
听	Supply and extract systems	听	3-5%
听	All air low velocity system	听	4-6%

Table 2: Space allowances for service ducts and shafts
Design area	Application	Other information	Rule of thumb
Air ducting	听	Typical ducting size	0路2 m²/m³/s
Lift shafts	Between 4-18 floors in office type buildings	Internal shaft area	听
听	听	A: floor area/storey (250 m² min)	听
听	听	N: floors	3 + A(n-4)/250 m²
Mechanical service riser	Simple pipework riser	Depth needed to open access door/size panel when width of door varies with /type of pipe or depth of service/duct	听
听	听	听	690 mm
Pipework	听	Pipe: 20 mm diamter	100 mm x 100 mm
听	听	Pipe 25 mm diameter	120 mm x 120 mm
听	听	Pipe: 32 mm diameter	130 mm x 130 mm
听	Three-sided riser	Minimum depth from service to (open) acess door/panel	690 mm
Service ducts	Vertical service duct	Floor space served by vertical service (radius)	15-23 m
听	听	Aspect ratio of vertical service duct	2:1 to 4:1
听	听	Total duct areas as a percentage of gross floor area	2%

Table 3: Space allowances for plant rooms (floor area)
Design area	Application	Other information	Rule of thumb
Air-cooled condensers and controls	听	Space for installation and maintenance	25 + kW/200 m²
Air handling units	听	With extract/recirculation	8 m² per m³/s
听	听	Without extract/recirculation	5 m² per m³/s
Boilers (percentage floor area)	Boiler plant and calorifiers	听	0路8-1路8%
听	听	Oil tank room	1-2%
Boilers (floor area and height)	Boilers, pumps, piping and space for installation and maintenance	Output 100kW	15 m² x 3 m
听	听	Output: 200 kW	25 m² x 3 m
听	听	Output: 1000 kW	80 m² x 4 m
听	听	Output: 4000 kW	140 m² x 5 m
Calorifiers (floor area and height)	Calorifiers, pumps, pipework, installation and maintenance controls and space for	Vertical: (1 m3)	10 m² x 3 m
听	听	Vertical (5 m3)	20 m² x 4 m
听	听	Vertical (10 m3)	25 m² x 5 m
听	听	Vertical (15 m3)	60 m² x 3 m
听	听	Horizontal (1 m3)	25 m² x 3 m
听	听	Horizontal (5 m3)	30 m² x 3 m
听	听	Horixontal (10 m3)	45 m² x 3 m
听	听	Horizontal (15 m3)	60 m² x 3 m
Chillers (water cooled)	With pumps, pressurisation, pipework and control panels	Output: 1000 kW	50 m² x 3 m
听	听	Output: 2000 kW	63 m² x 3 m
听	听	Output: 3000 kW	83 m² x 3路5 m
听	听	Output: 4000 kW	108 m² x 4 m
Chillers (air-cooled)	Located outside, includes space for installation and maintenance	Output: 200 kW	39 m²
听	听	Output: 400 kW	53 m²
听	听	Output: 600 kW	75 m²
听	听	Output: 800 kW	84 m²
听	听	Output 1000 kW	98 m²
听	听	Output: 1200 kW	116 m²
Cold water storage	Single cold water tank. Includes space for installation and maintenance but add space for pressurisation plant or circulation pumps	FA: floor area	听
听	听	V: gross storage m²	听
听	听	1 m high	FA: 10 + V/0路75 m²
听	听	2 m high	FA: 10 + V/1路6 m²
听	听	3 m high	FA: 10 + V/2.4 m²
Cold water storage	Minimum storage for hot and cold outlets	Office 鈥� with canteen	45 litres/person
听	听	Office 鈥� no canteen	40 litres/person
听	听	Hotel	135 litres/bed space
听	听	Hostel	90 litres/bed space
听	听	Restaurant	7 litres/meal
听	听	Day school	15-20 litres/pupil
听	听	Boarding school	90 litres/pupil
听	听	Children鈥檚 home or residential nursery	135 litres/bed space
听	听	Nurses鈥� home	120 litres/bed space
听	听	Nursing or convalescent home	135 litres/bed space
Hot water storage	Minimum storage capacity	Dwellings	115 litres/bedroom
听	听	Students and nurses鈥� homes	20 litres/bed space
听	听	Children鈥檚 home, elderly sheltered and elderly care home	25 litres/bed space
听	听	Hostels, budget	35 litres/bedroom
听	听	Hotels, 4/5 star	45 litres/bedroom
听	听	Offices, shops and factories	5 litres/person
听	听	Schools: nursery, primary, secondary	5 litres/person
听	听	Schools, boarding	25 litres/person
听	听	Hospitals: district general, surgical ward and medical ward	50 litres/bed
听	听	Hospitals: paediatric	70 litres/bed
听	听	Hospitals: geriatric	40 litres/bed
听	听	Sports changing: sports hall and swimming pool	20 litres/person
听	听	Sports changing: field and all-weather pitch	35 litres/person
听	听	Places of assembly such as libraries, museums and cinemas (excluding staff)	1 litre/person
Cooling towers	听	FA: floor area (kW: heat rejection)	FA: 50 + Kw/66 m²
Sub-station	200 kVA transformers	听	47 m²
听	Switchgear	HV switchgear	14 m²
听	听	HV + lv switchgear	27 m²
Standby generation	Standby sets and accessories	FA: floor area	FA: 15 + kVA/30 m²
Uninterruptible power supply	Single module system (add space for batteries)	听	听
听	听	FA: floor area	FA: (2+ kW/200) x 2 m²

Table 4: Miscellaneous services
Design area	Application	Other information	Rules of thumb
Control panels and distribution boards	Front panel controls, wall mounted or floor standing	Fixed height range (above finished floor or operating platform level)	1200-1800 mm
LTHW boiler plant (component criteria for leakage containment)	Oil storage tanks, distilate and residual fuel oils	If tank fails, walls and doors treated to contain spillage	Tank contents + 10%

Table 5: Space allowances for on-floor services (depth of clear space in ceiling/floor void)
Design area	Application	Other information	Rule of thumb
Air conditioning	VAV	听	350-750 mm
听	VRV	听	450 mm
听	Recessed chilled beams	听	350-450 mm
听	Surface chilled beams	听	250 mm
听	Chilled ceilings	听	250 mm
听	Fan coils	听	450 mm
听	Ducted air systems	听	450 mm
Drainage	听	100 mm diameter	10-25 mm per m run
听	Solid waste	150 mm diamtere	7-16 mm per m run
Lighting	Fluorescent	听	100-150 mm (+access)
听	Downlighter	听	150-300 mm
Power and communications	Multi-core cables and lighting cables	听	100-200 mm
听	Power and data (heavy line)	听	200-250 mm
听	Computer rooms	听	300 mm

Table 6: Space allowances for catering facilities
Design area	Application	Other information	Rule of thumb
Kitchen and dining facilities	Kitchens including preparation and storage	Minimum needs:	听
听	听	Up to 100 meals	0路4 m²/meal
听	听	Up to 500 meals	0路25 m²/meal
听	For single sittings	Ratio of kitchen space to dining space	0路33:1 to 0路5:1
听	For multiple sittings	Ratio of kitchen space to dining space	1:1

Table 7: Floor allowance per occupant (net internal area)
Design area	Application	Other information	Rule of thumb
General offices	听	听	12-17 m²/person
Trading desks, call centres, workstations	听	听	4-6 m²/person
Enclosed offices	听	听	15 m² (or more) per person

Table 8: Plant weight allowances
Design area	Application	Other information	Rule of thumb
Single boiler	500 kW	听	1500 kg
听	1500 kW	听	4250 kg
听	2500 kW	听	6500 kg
Single storage steel calorifier	4 m³	听	1250 kg
听	8 m³	听	2500 kg
听	12 m³	听	3300 kg
Single non-storage mild steel heating calorifier	500 kW	听	150 kg
听	1000 kW	听	225 kg
听	1500 kW	听	275 kg
听	2000 kW	听	325 kg
Single water cooled liquid chiller	1500 kW	听	10 000 kg
听	3000 kW	听	20 000 kg
听	4500 kW	听	30 000 kg
Single air-cooled liquid chiller	500 kW	听	6000 kg
听	1000 kW	听	11 000 kg
听	1500 kW	听	14 000 kg
Single generator	500 kVA	听	5000 kg
听	1000 kVA	听	8000 kg
听	1500 kVA	听	11 0000 kg
Single ups system	100 kVA	听	1250 kg
听	300 kVA	听	2750 kg
听	500 kVA	听	4250 kg

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