Ventilation and Air Conditioning
avoid/reduce air conditioning
- temperature setpoint for air conditioned IT/comms rooms to around 25degC rather than a lower temperature (7)
- air conditioning setpoint temperatures in the general office space to 24degC (10)
- air conditioning time controls to match period of operation to occupancy (10)
- air conditioning controls to avoid concurrent heating and cooling in the same zone (10)
Use 'passive' before 'active' solutions by giving preference to natural ventilation
- draw cooler air from a shaded side of the building in order to maximise the cooling potential (18 - section 2.2)
- plan the air flow path through the building (18 - section 2.2)
- openable windows even if building is to be mechanically ventilated (1 - credit HW8, 18 - section 2)
- heat gains to the space minimised by careful design of the building envelope (8 - section 7.2)
- internal heat gains from lighting, office equipment etc. below the average heat emissions from equipment given in CIBSE Guide F Section 12 Table 12.5 & 12.6 (8 - table 12.6)
- internal heat gains from lighting, office equipment etc. below the average heat emissions from equipment given in CIBSE Guide F Section 12 Table 12.5 & 12.7 (13 - section 6)
- meet the cooling requirements with free or passive cooling sources (e.g. displacement ventilation, chilled beams) (8 - section 07/03/02, 15 - section 4, 12 - section 2, 5, 2)
Consider recovering heat by extracting air through luminaires to recover a proportion of the energy consumed by the lamps
- recover heat by extracting air through luminaires to recover a proportion of the energy consumed by the lamps (8 - section 07/03/05)
Consider energy recovery between air streams
- include heat recovery as an integral part of the overall design (8 - section 07/02/02)
- reduce the risk of cross-contamination between air streams when designing the system (8 - section 4.2.5.5)
Consider external factors that might restrict the choice of natural ventilation, such as noise and air pollution
- air intakes or openable windows at least 20m away from sources of external pollution, such as roads, car parks etc (18 - section 2.2, 4 - section 3, 1 - credit HW9)
Consider methods of minimising energy demand for ventilation purposes
- keep mechanical ventilation rates to a minimum commensurate with acceptable levels of indoor air quality (8 - section 7.2, 15 - section 3, 17, 16, 9)
- consider meeting comfort requirements using mechanical ventilation alone without mechanical cooling (8 - section 7.2.3.1)
Avoid the control of humidity (humidification and de-humidification) unless humidity needs to be controlled within very specific levels (e.g. museums, labs)
- if humidification is necessary, design in accordance with available good practice guidance (8 - table 7.4, 15 - section 4, 11)
The four main ways of reducing fan energy consumption are: optimising the fan characteristic; efficient system regulation; reducing air transport losses; switching off the system when not required
- distribute air effectively by avoiding excessive duct lengths, system resistance and duct heat loss (8 - section 07/03/06, 19 - section 2.11, 14)
Use effective controls through good zoning, effective time control, and variable flow control where possible
- effective BMS control of plant operation to deliver target comfort conditions during occupied hours in each zone of the building ()
- select controls for mechanical ventilation systems in accordance with available good practice guidance (8 - table 7.8, 15, 6 - section 5, 3)
Consider a mixed mode system if full natural ventilation is not an option
- mixed mode ventilation system (8 - section 07/02/01, 20)
Reference Documents
| Series Number | Publisher | Title | |
|---|---|---|---|
| 1 | BRE | BREEAM 2006 | |
| 2 | BG 8/2004 | BSRIA | Free Cooling Systems |
| 3 | GIR 41 | Carbon Trust | Variable flow control |
| 4 | TM21 | CIBSE | Minimising pollution at air intakes |
| 5 | TN 2/96 | BSRIA | Displacement ventilation and chilled ceilings |
| 6 | Guide H | CIBSE | Building control systems |
| 7 | Carbon Trust | Focus - the manager's guide to reducing energy bills | |
| 8 | Guide F | CIBSE | Energy efficiency in buildings |
| 9 | GPG 257 | Carbon Trust | Energy efficient mechanical ventilation systems |
| 10 | BRE | The Office Toolkit - the guide for facilities and office managers for reducing costs and environmental impact | |
| 11 | AG10/94 | BSRIA | Efficient humidification in buildings |
| 12 | GIR 85 | Carbon Trust | New ways of cooling |
| 13 | Guide A | CIBSE | Environmental design |
| 14 | GPG 33 | Carbon Trust | Energy efficiency in offices - Understanding energy use in your office |
| 15 | Guide B2 | CIBSE | Ventilation and air conditioning |
| 16 | GPG 71 | Carbon Trust | Selecting air conditioning systems. A guide for building clients and their advisers |
| 17 | TN 15/92 | BSRIA | Refrigeration and the Environment: Typical Applications for Air Conditioning |
| 18 | AM10 | CIBSE | Natural ventilation in non-domestic buildings |
| 19 | Guide B3 | CIBSE | Ductwork |
| 20 | AM13 | CIBSE | Mixed Mode Ventilation |