AET Flexible Space and the WELL Building Standard - AET Flexible SpaceAET Flexible Space

AET Flexible Space and the WELL Building Standard


AET Flexible Space System (Under Floor Air conditioning) and the WELL STANDARD

The WELL Building Standard promotes clean air through reducing or minimising the sources of indoor air pollution, requiring optimal indoor air quality to support the health and well being of building Occupants.

FSS Impacts on the following sectors of the of the AIR Feature Level Matrix and Comfort Feature Level Matrix  sectors and to some extent supports other sectors in italicised print.


AIR Feature Level Matrix


1.0 Air Quality Standards

Intent: To ensure a basic level of high indoor air quality

The good quality and easily adjusted fresh air ventilation of the system aids the attainment of this standard


2.0 Smoking Ban

Intent: to deter smoking,minimise occupant exposure to secondhand smoke and reduce smoke pollution

Selection of fresh air intake positions away from smoking areas is essential for all ventilation systems. Restrictions on smoking near to entrances and windows should be considered.


3.0 Ventilation Effectiveness.

Intent: To ensure adequate ventilation and high indoor air quality

Fresh treated air is delivered close to the occupant without having to come down through layers of pollution retained in the stratified air of conventional ceiling based systems.

The fresh air can be demand controlled either on temperature variation or on CO2 increase/decrease

The systems are virtually self balancing due to the low void pressures and the fan assisted damper controlled terminals.


4.0 VOC Reduction

Intent: to minimise the effect of VOC’s in building materials on Indoor Air Quality

The ventilation effectiveness of the system provides good dilution of such pollutant.


5.0 Air Filtration

Intent:to remove indoor and outdoor airborne contaminants through air filtration

Zone units can be supplied with a variety of filter grades and techniques tailor made to suit the zone in question. Normally pleated Filter material of EU5 standard is supplied but this can be increased to EU7 and above, achieving further improvement in IAQ but reducing Units airflow and capacity and increasing frequency of filter change and thus maintenance costs. Centralised systems cannot offer such flexibility.

Zone units can be supplied with Carbon Filters and/or UV elements and Electrostatic Filters. Zone Units are often less than 20m away from the people they serve so there is no long contaminated ductwork path to follow after filtration.

Fan assisted terminals  located near to users can also be supplied with particulate filters of varying grades.


6.0 Microbe and Mould Control

Intent: To reduce mould and bacteria growth within buildings particularly as a result of water damage or condensation on cooling coils.

Microbe problems and Mould usually occur in buildings with high humidity and dampness. Zone units can be full function AC units with Dehumidification and Humidification control as standard. Normal office RH will be in the range 40-60% and as such Mould and Bacteria are less likely to occur.

Zone units are floor standing and easily accessed for maintenance and if required coils can be steam cleaned periodically to eliminate mould etc.

The use of floor voids rather than ductwork for air distribution increases the flushing and drying of hidden cavities to some extent. Warm air heating and the associated air change rates of the system in winter when external Humidity is generally the highest, helps to avoid interstitial condensation within the structural slabs.


7.0 Construction pollution Management     

Intent: To minimise the introduction of construction related pollutants into indoor air and protect building products from degredation

Part 1. Ductwork is minimised and floor voids are easily accessed for cleaning. All normal protection procedures are employed.

Part 2. Filter replacement. In considering the cleanliness of the indoor air for construction workers the Zone Units if installed at an early stage can be used as local air filtration units and at handover the units can be cleaned and the filter cartridges replaced for occupation.

Part 3. Moisture absorption Management. Separate zones can be arranged utilising the zone units as specific conditioned storage points  for absorptive materials such as ceiling tiles, carpets and furnishings.


8.0 Healthy Entrance

Intent: to minimise the introduction of pollutants into indoor air at building entrances

Positive pressurisation through selected ventilation volume ensure minimum infiltration.


9.0 Cleaning Protocols.

Intent: To reduce occupant exposure to pathogens,allergens and harmful cleaning chemicals

IAQ  within the work space is constantly varying due to the various activities,climatic conditions and pollution levels from indoors and externally. The Flexible Space System is inherently easy to access for maintenance and cleaning. Floor voids can be vacuumed periodically and in extreme conditions can be steam cleaned. Such access is dramatically easier to achieve than ceiling based ducted systems and thus cleaning is more easily and more often performed, as a result.

The World Health Organisation and other bodies such as ASHRAE publish figures for safe levels of exposure to a variety of pollutants. However what they don’t show is the safe level of the potential cocktail of pollutant that an average office worker breathes every day.

Indoor Air Quality test results – ALVIKS Strand – Stockholm
Source: Healthy Buildings Inc.


Source: Healthy Buildings Inc



Every day the average human being will consume 2kg of liquid 1 kg of dry food and 24kg of air.We assume the air hygene from ducts etc is as good as our food and liquid hygene from shops and restaurants. But is it? As engineers it is important that we pay as much attention to the air quality as hygienists pay to food production, packaging and delivery techniques.


CENTRAL VACUUM CLEANING: It is also possible to include a central vacuum cleaning system making use of the floor void and risers to house the associated pipework, with hose points set in the raised access floor panels.Conventional vacuum cleaners simply deliver fine dust particulate back into the work space as evidenced by the fine brown dust on computer screens.Central vacuum systems remove all particle to a centrifuge away from the working space.


10.0 Pesticide Management

Intent: to reduce the presence of pests in buildings and minimising occupant exposure to harmful chemicals

The good ventilation of the system supports this.


11.0 Fundamental Material Safety

Intent: to reduce or eliminate occupant exposure to lead,asbestosand PCB’s from building materials

Filtration and ventilation aids this.


12.0  Moisture Management

Intent: to limit the potential for bacteria and mould growth within buildings from water infiltration and condensation

Part 2: Raised floor voids can house a variety of services including data and power cabling and terminals, pipework and insulation etc. In the event that a major leakage of water within the building occurs water will enter the floor voids and risers. This crisis is more easily dealt with than systems employing in screed power systems and inslab conduits  where immediate access is impaired. Additionally the floor void being fully ventilated can reduce the drying time and avoid mould growth etc from occurring.

Part 3: Condensation rarely occurs in the floor voids of this system and if ever it did it is easily dealt with in the same way.Water detection sensors can be added to the system controls to set off alarms.


13.0 Airflush

Intent: to remediate construction related indoor air contamination.

Buildings utilising the Flexible Space System can make use of air purging at any time. (Usually Night Time for energy saving) In the event of a high VOC level after a newly completed construction or fitout later in the life of the building the controls of the system can be set to drive increased fresh air through the voids and the occupied spaces to reduce such pollution before occupation. The controls and associated heating and cooling elements of the system ensure that the building does not suffer stress resulting in condensation, low or high temperatures  or other undesirable affect.


14.0 Air Infiltration Management

Intent: To minimize air quality and thermal comfort issues resulting from the infiltration of untreated air through the building envelope.

The Flexible Space System utilises several construction elements when creating the air paths and as a result the air tightness of these elements is paramount to the success of the system. As a result buildings utilising this system are inherently more airtight and thus avoid excessive infiltration, pests and debris and mould spores.


15.0 Increased Ventilation

Intent: To expel the internally generated pollutants through an increased supply of outdoor air

Many buildings undergo constant change of space arrangements, occupation levels and working practices. With conventional fully ducted systems it is difficult and often very expensive to bring about major changes in ventilation volumes due to the extent of ductwork changes,ceiling void disruption and suchlike. With floor plenum systems the vertical riser ductwork simply feeds air to a number of fresh air control dampers within the floor void. These dampers in most cases can be manually   adjusted in line with such changes in occupancy. Where close control of air quality is desired to mange CO2 and other pollutants automatic control of the dampers can be employed along with Variable speed drives on the central ventilation plant.


16.0  Humidity Control

Intent: To limit the growth of pathogens,reduce off gassing and maintain thermal comfort by providing the appropriate level of humidity

For human comfort and the avoidance of dry eyes,dry skin etc humidity in the work space is important and should be controlled in line with CIBSE and ASHRAE recommendations. Usually between  40%-60%. The Flexible Space System employing zonal humidity control can offer far closer control than averaged central fresh air based humidity control which can only average the demand.

Pathogen control can be achieved more effectively as a result. If humidity levels are allowed to creep up off gassing can be increased. Formaldehide emissions for example can increase by a factor of 2 or more with increasing humidity in the occupied space.


17.0  Direct Source Ventilation

Intent: to preserve air quality in occupied spaces through the isolation and proper ventilation of indoor pollution sources and chemical storage areas.

The use of modular fresh air boosters can bring additional fresh air through the floor void to specific locations and can be controlled manually or automatically.


18.0 Air Quality

Intent: To monitor and effectively remediate indoor air quality issues and inform building managers and occupants of the quality of the indoor air

 CO2 monitoring Data recording possibility. Temperature and Humidity zone by zone standard through Flexmatic and FLEXVISOR


20.0 Dedicated outdoor air systems

Intent: to allow buildings to control the outdoor air supply independently from the heating/cooling needs of the building

The system provides Fresh air plant with heat recovery to minimise the dependence on the installed air conditioning and heating systems to meet the varying heating and cooling demands of the fresh air.


21.0 Displacement systems

Intent: to improve air quality in the breathing zone of the room and maintain thermal comfort by supplying low velocity outdoor air  near the floor and expelling near the ceiling.

With CAM-V and swirl grilles it is possible to create a displacement system on a zone by zone basis. However fan assisted terminals with optional trim heaters offer increased personal control and centralised control of temperature and air movement with reduced numbers of outlets generally. Meeting rooms and other variable load rooms are better serviced with this technique. In addition local fan assisted terminal can incorporate filtration to improve air quality.Standard floor grilles offer no meaningful control beyond a manually adjustable damper to set the air flow.


22.0 Pest Control

Intent: to reduce the presence of pests in buildings and minimise occupant exposure to pest related allergens

Whilst not offering a pest control solution the accessibility of the system makes it far easier to clean and to remove debris, caused by such infestation when  compared with ductwork systems. Often such infestation goes unnoticed in ductwork due to lack of access but if such infestation occurs in a floor void it is often found much more quickly and is easily dealt with. A survey carried out by the CIBSE found 21/2 dead cats in the supply duct to a hospital operating theatre.


23.0 Advanced Purification

Intent: To improve recirculated indoor air quality through the implementation of advanced air purification strategies.

Various solutions can be installed in the Zone units generally.  UV light,Carbon Filtration,Photocatalytic Oxidation,Ozone , high grade eu7 improve the purity.


24.0 Combustion Minimisation

Intent: to reduce occupant exposure to combustion related air pollution from heating and transportation sources

Selection of appropriate heating equipment, avoidance of short circuiting of exhaust into fresh air intakes and entrances. Avoidance of traffic fume as far as possible in building carparks etc by appropriate ventilation. Whilst not controlling the production of such pollution The Flexible Space System ensures good dilution of pollutants within the occupied area.


25.0 Toxic Material reduction

Intent: to minimise the impact of hazardous building material chemicals on indoor air quality and protect the health of manufacturing and maintenance workers.

Whilst not controlling the production of such pollution The Flexible Space System ensures good dilution of pollutants within the occupied area.


26.0 Enhanced Material Safety

Intent: to minimise the impact of hazardous building material ingredients on indoor air quality and and protect the health of manufacturing and maintenance workers.

Whilst not controlling the production of such pollution The Flexible Space System ensures good  filtration and reduction  of pollutants within the occupied area.


27.0 Anti microbial activity for surfaces

Intent: to reduce occupant exposure to both harmful pathogens and hazardous cleaning materials

Humidity control in the space, provided by the Flexible Space System, helps to reduce the production of microbes and mould.


28.0 Cleanable Environment

Intent: to reduce occupant exposure to pathogens on high touch surfaces.

The components of the Flexible Space system have been considered from a cleaning perspective but this refers more to door handles, work surfaces etc.


29.0 Cleaning equipment

Intent: to reduce occupant exposure to both harmful pathogens and hazardous chemicals through the use of high quality cleaning equipment and the proper storage of cleaning agents

Whilst not controlling the production of such pollution The Flexible Space System ensures good dilution and filtration of pollutants within the occupied area.




75.0 Internally generated Noise

Intent: to reduce acoustic disruptions and increase speech privacy by creating and acoustic plan and limiting indoor noise levels.

The Flexible Space System is inherently quiet in operation. Users are able to adjust the fan speed of their Fan assisted terminals for temperature and air movement and in adjusting the fan speed they are able to introduce more or less white noise to assist in speech privacy in open plan offices in particular.


76.0 Thermal Comfort

Intent: to promote occupant productivity and ensure a sufficient level of thermal comfort

It is not possible to satisfy everyone at all times in their work space. Women prefer warmer temperatures than Men generally. The Flexible Space System offers a high level of personal control of room temperature and air flow compared with conventional systems and as space changes adjustments to air terminal positions can be made quickly and at little cost.


77 Olfactory comfort

Intent: to maximise olfactory comfort by reducing the transmission of strong smells  and odors within the building.

The zonal concept of the Flexible Space System aids in the control of odour transmission in 2 ways. Physical separation and high grade odour filtration (Carbon Filters) Conventional  recirculatory ducted systems tend to carry odours throughout a building.


81.0 Sound Barriers

Intent: to reduce sound transmission and acoustic disruptions by the application of sound barriers

Using the floor void for both supply and return of conditioned air ceiling voids can be eliminated, doing away with the need for expensive acoustic barriers over partitions. Raised floors have far higher acoustic qualities than ceilings generally. Where acoustic treatment is required in the floor void it is a simple matter to add acoustic material. On going during the life of the building adaptions can be easily carried out with minimum dispruption and cost.


82.0 Individual Thermal Comfort

Intent: to maximise and personalise thermal comfort among all occupants

The very nature of the personal control of the fan assisted terminals permits a very high level of personal adjustment to suit individual requirements. Whilst open plan spaces are less easy to control the provision of fan assisted terminals with trim heater, fan and temperature adjustment permits users to position the units where they like and set them to operate as they like. This is one of the key features of the system over conventional ceiling based systems and indeed conventional Displacement Systems where considerable complaint of temperature and draught has been recorded.

In some projects women have requested a fan terminal be positioned under their chair so they can create their own micro environment by adjusting the temperature set point and the fan speed. Much like spot cooling in a high bay factory or foundary the fan terminal provides localised comfort adjustable  by the user.



General Description        

 The Flexible Space CAM-V System is an under floor air-conditioning system making use of the raised floor void for the distribution of supply air without conventional ductwork. Ductwork is very inflexible to suit changing requirements and also difficult and expensive to clean. Segregated zones in the floor plenum are defined using zone barriers. Conditioned Air Modules (CAM-Vs) are suitably located throughout the office space to serve each zone and provide conditioned air locally to suit the requirements of the space. CAM-V units supply conditioned air to the floor void supply plenum and draw spent air back at high level either within the space or via a return air plenum.

Chilled and heating water are delivered to the CAM-V units by means of suitably-sized insulated piping – all pipework within the raised floor voids being of copper with vapour-sealed closed-cell Armaflex insulation to minimize pipe diameters, and, therefore, impedance to airflows. Condensate water is drained from CAM-V units as illustrated in the CAM-V manual.

Fresh air is delivered directly to the return air section of a CAM-V at high level.  The fresh air can be treated either from a central ducted ventilation system or directly by the CAM-V from FSS Fresh Air Modules located at high or low level. Extract air is typically removed from high level extract louvres close to risers.

Individual  personal controllable fan terminals of either recessed (Fantile) or floor-standing (Console Terminal) type are set into the supply sections of the raised floor voids.Users are able to ajust Temperature set points and fan speeds to vary the flow of air into their space. These terminals are network-linked to their respective CAMs for efficient and co-ordinated control. Fantiles or Console Terminals deliver air from the raised floor void to the space above according to the demands of their integral Fatronic controllers. They also provide data to CAM’s in order to ensure the optimal operation of each CAM.

Where personal control is not required in areas such as Stores or Photo copy rooms standard round Swirl grilles can be employed but there is no temperature or draught  control with these.

Buildings are generally divided into several zones per floor and these zones are defined by means of zone barriers installed in the floor void. The use of fan assisted terminals avpids the common problem of air starvation in parts of the floor void where tenants have added cablke trays etc causing air flow restriction or redirection away from outlets. Fans in the units pull air towards them regardless of such restrictions giving much improved performance.

The zone units (CAM-Vs) within each floor are similarly data-linked to common Flexmatic displays that can be easily relocated and adjusted locally.





  • Flexibility with regard to future CAT B fit out/layout changes.


  • No need for ceiling void in open plan zones, avoiding dust trap above work space,avoiding cross talk attenuators


  • Increased finished floor height/decorated soffit height permits greater spread of daylight.


  • Standard 300mm o/a floor makeup (270 clear floor void). 180/200mm clear floor void with low height terminal.


  • Simplicity of moving fantile terminals for churn and to suit user comfort.


  • Ideally suited for buildings with multiple zones.


  • Can be used in common floor plenums (with Run and Standby facility if required).


  • End user/owner occupier terminal control.


  • Ideally suited to cellular office applications.


  • No need for wiring in partitions.


  • Excellent temperature control and quick response to change in heat gains to the space and/or control settings.


  • Minimal on floor ductwork and pipework services.


  • Flexible Space system only needs a relatively small air handling unit plant for the fresh air.


  • No filter in the Fantile terminal to be maintained.


  • Fantile electric and hot water heating options available.


  • Regular maintenance restricted to CAM-V downflow units.