Heating ventilation and air conditioning HVAC
'HVAC' refers to Heating Ventilation and Air Conditioning, which can be used in buildings to:
- Maintain internal air quality.
- Regulate internal temperatures.
- Regulate internal humidity.
It is sometimes extended to include other services, such as refrigeration (HVACR).
Internal air quality can be maintained by a combination of introducing 'fresh' air into the building, extracting 'stale air' and by filtration. Ventilation may be natural, mechanical, or mixed mode (a hybrid system). See Ventilation for more information.
Internal temperatures can be regulated by heating and cooling. Typically, this is achieved by heated water (or sometimes steam) and chilled water that is generated by boilers and chillers and then used in heating coils and cooling coils as part of the ventilation system. Alternatively, hot water may be used to supply systems such as radiators, underfloor heating and so on.
Humidity can be regulated by ventilation, dehumidification and humidification. Dehumidification is often provided alongside cooling as cooling air reduces the amount of moisture air is able to 'hold', resulting in condensation. 'Close' humidity control (to within 10%) can involve cooling and dehumidification, then re-heating and re-humidification.
Very broadly, HVAC systems can be centralised in a building, or local to the space they are serving, or a combination of both (for example, local air handling units supplied by centrally-generated cooling). They may also be connected to a wider district heating or cooling network.
They may be integrated, with heating, ventilation and air conditioning provided by a single system, for example, air handling units connected to ductwork, or they may be a combination of separate systems, for example mechanical ventilation with radiators for heating and local comfort cooling units.
They may also include passive (or 'natural') systems such as natural ventilation.
In mechanically ventilated commercial developments, HVAC is often provided by air handling units (AHU) connected to ductwork that supplies air to and extracts air from internal spaces. Air handling units typically comprise an insulated box that might include some, or all of the following components; filter racks or chambers, a fan (or blower), heating elements, cooling elements, dehumidification, sound attenuators and dampers. Air handling units that consist of only a fan and a heating or cooling element, located within the space they are serving, may be referred to as fan coil units (FCU). See Air handling units for more information.
HVAC can consume large amounts of energy, and where possible, demand should be reduced and passive systems adopted.
Extracting internal air and replacing it with outside air can increase the need for heating and cooling. This can be reduced by re-circulating a proportion of internal air, or by heat recovery ventilation (HRV) that recovers heat from extract air and uses it to pre-heat incoming fresh air.
It is important that all aspects of HVAC systems are considered together during the design process, even where involve independent systems. This is because of the interaction between heating, cooling, humidity control and ventilation. This is particularly complicated when other elements of environmental behaviour are considered such as solar gain, natural ventilation, thermal mass, and so on.
The design of HVAC systems is generally a specialist task, undertaken by a building services engineer, and because of its interaction with other elements of the building it is important that it is considered from the outset, as a fundamental part of the design process, and not an 'add on' at the end.
HVAC may be controlled by a building management system to maximise occupant comfort and minimise energy consumption.
Regular inspection and maintenance is necessary to ensure that systems are operating optimally.
[edit] Related articles on Designing Buildings
- 2021 UK HVAC trends: winners and losers.
- Air conditioning.
- Air conditioning inspection.
- Air filtration.
- Air handling unit.
- Air pressure drop APD.
- Amber warnings raise building overheating concern.
- Back to the workplace: are you prepared?
- Biological fouling.
- BSRIA announces 2021 European HVAC field device study.
- BSRIA Briefing 2021.
- BSRIA Indoor Air Quality TG 12/2021.
- BSRIA study: The market for European Field Devices.
- BSRIA Water Treatment for Closed Heating and Cooling Systems BG 50/2021.
- Building energy management systems (BEMS) for data centres.
- Building engineering physics.
- Building management systems.
- Building services
- Building services engineer.
- Can the Zeroth Energy System reduce the carbon footprint of HVAC services?
- CFD.
- Chilled beam.
- Chiller unit.
- Chilled water.
- Clean air delivery rate CADR.
- Cooling systems for buildings.
- Constant air volume.
- Dehumidification.
- Designing HVAC to resist harmful microorganisms.
- Displacement ventilation.
- Drivers of change in global heating markets.
- Ductwork.
- Electrical control systems.
- European decarbonisation and heating technologies beyond 2021.
- Evaporative cooling.
- Fan coils.
- Fan coil unit.
- Growing focus on IAQ challenges for specifiers and HVAC manufacturers.
- Heat pump COP & EER and central plant SCOP in ambient loops.
- Heat recovery.
- Heating.
- How does a chilled water fan coil unit work?
- Humidification.
- Humidistat.
- Humidity.
- HVAC 2030: BSRIA puts opportunities and challenges to the industry.
- HVAC balancing.
- Hybrid heat pump electric panel heating.
- IAQ developments accelerated by COVID-19 pandemic.
- Mechanical, electrical and plumbing MEP.
- Mechanical ventilation.
- MedicAir air purification technology.
- Minimum efficiency reporting value MERV.
- Natural ventilation.
- Plant room.
- Radiant heating.
- Retrofit, refurbishment and the growth of connected HVAC technology.
- School reopening and indoor air quality in North America.
- Smart connected HVAC market.
- Tempering heating.
- Thermal comfort.
- Training for pre-commissioning cleaning of pipework systems.
- US recommits to clean energy.
- US water heating market update 2021.
- UV disinfection of building air to remove harmful bacteria and viruses.
- Variable air volume VAV.
- Variable refrigerant flow.
- Ventilation.
- What are the different types of heat pumps and where would you use them?
[edit] External references
Featured articles and news
Landownership in England in 1909
A national valuation to fund old-age pensions.
The world’s largest Commonwealth memorial to the missing.
Long after the end of the defects liability period.
BSRIA Occupant Wellbeing survey BOW
Occupant satisfaction and wellbeing in buildings.
Geometric form and buildings in brief
From the simple to the complex.
Understanding the changing nature of insulation
And the UK Government guidelines.
Three year action plan to improve equity, diversity and inclusion
Commitment agreed to by major built environment bodies.
The Construction Route – what needs to change?
Electrical skills, low carbon, high-tech and the building services revolution.
Deep geothermal power possibilities
Ultra-deep drilling with millimeter-wave beam technology.
BSRIA Briefing 2022- From the outside looking in
Looking at the built environment from space.
Competence requirements for principal contractors and designers
BSI standards 8671, 8672 and 8673.
Bringing life to burial grounds.
From failed modernism to twenty-minute neighbourhoods.
Design chill and design freeze
The gates process and change control.
Neuroscience for project success
Why people behave as they do. APM book.
Comments
Ventilation systems help maintain a healthy environment by regulating moisture and humidity, controlling temperatures, removing contaminated or stale air, ridding the air of dust or allergens, providing the proper exchange of oxygen and carbon dioxide levels and exchanging fresh air throughout a confined space or spaces. Ventilation systems are used in various settings including homes and workplaces.