Air conditioning
This is a term generally used for air conditioning solutions ( heating and cooling ) within office areas even though this can extend to warehouse and other working environments. Comfort cooling parameters are generally designed around 23-24° C with no real attention paid to the relative humidity ( RH ) of the space served (example of simple office comfort cooling installation plan).
We also install systems to meet specialist demands - such as those required by the converging Information Technology and Communications (ICT) Industries. Examples would include systems for computer rooms or data centres which have seen a growth explosion in recent years.
System Concepts
Inverter systems offer considerably increasing system performance and efficiency, whilst significantly reducing running costs. Inverter products are so efficient and 'green' that the government endorses such installations by allowing companies to claim Enhanced Capital Allowances (ECA's), making this a very tax efficient purchase indeed. For further information, refer to the Government's website on Enhanced Capital Allowances at: http://www.eca.gov.uk.
 |
Systems are totally automated and will switch between heating and cooling as required. Systems are far more efficient to run than conventional electric heating offering a coefficient of performance (COP) of between 2 and 3. In layman's terms, this means every input watt multiplied by the COP gives the output performance in watts or kilowatts. When this is compared to a traditional electric heater offering 1kw input to 1kw output, this offers high potential cost savings. DX (direct expansion) type air conditioning systems are among the most efficient forms of cooling concepts available. They can incorporate VRV / VRF technology ( Variable Refrigerant Volume / Flow ) using inverter technology outlined above. Direct expansion systems produce a cooling effect via a single process of heat exchange and do not use water as a cooling medium which has may advantages, especially when looking at smaller installations. System styles can be wall-mounted, ceiling cassettes, ducted or otherwise. A few examples are pictured below: |
| Wall mounted All systems that fix directly onto a wall at high level, normally returning the air via the front fascia and discharging the air via a single louvred discharge assembly at the top or bottom of the unit. This system is among the the most cost-effective solutions but is not so efficient or effective in larger, open-plan offices. This system ideally suits cellular offices up to 60 square metres.
|
 |
| Ceiling suspended This version is usually of the same appearance as the floor mounted system and identical in operation. Floor mounted and ceiling suspended systems normally double up as one mode to suit both applications. This system hangs directly beneath the ceiling and is especially effective where long throws are required. Generally, this is chosen as a substitute for a cassette where void space is not available.
|
 |
| Ceiling cassette This system is ideally located centrally within the ceiling itself. The only part of the system visible is the grille which protrudes the ceiling by between 10 and 20 mm. All internal workings are hidden above the ceiling where 300 to 400 mm void space is required for access. These systems return all air through the centre of the fascia and discharge through the sides. Its attributes of space saving and its ability to provide an even flow within large, open-plan areas make this a very popular option. Other benefits are its very low noise levels, due to the reduced air velocity through the four sides which also helps reduce any draughts or dead zones. This system is one of the most aesthetically pleasing and efficient available.
|
 |
| Floor mounted These systems are used where high-level wall space is valuable and no ceiling space is available. They return air via the front fascia and discharge air through the top louvred discharge assembly - ideal as a storage heater replacement. These systems can be as effective as, say, a ceiling cassette in heat pump mode, but less so in the cooling cycle due to air flow characteristics. |
 |
Heat pump is a term for a system capable of producing heating and cooling from one single installation. In cooling mode, the system is as you would expect but in heating mode, the system changes to a forced air heating system by reversing its operation internally. Both systems are aesthetically similar and the same installation practices are adopted. In heating mode, this can achieve room temperatures up to 28ºC and may be controlled thermostatically between 19ºC and 28ºC.
All systems are designed to cool to 23° C (+/-1ºC) in summer conditions when the external temperature is at 30ºC. Systems will operate up to a 40° C ambient, at a loss in performance and will lower temperatures in conditions milder than this if desired. These systems are fully automated and will achieve a room temperature of between 20ºC and 27ºC, depending on the thermostat setting and ambient condition. Air Options will and can tailor the customer's system to suit any temperature requirement but this may of course have an affect upon the budget.
Chilled Water (CHW) is generally the name for a system which uses water as a secondary cooling medium. Water chillers are used for larger projects and can look after entire buildings from a single item of plant. Water chilled solutions are more expensive and labour intensive and therefore normally installed into buildings as part of the initial build, as opposed to retro-fitting.
Water chilled services can be installed in ABS / PVC plastic or stainless steel / galvanised steel dependant upon the specification and requirement laid down by the client. As standard we use galvanised steel and ABS plastic.
Air cooled chillers can be supplied eliminating the need for a cooling tower or closed loop heat rejection circuit (air cooled as opposed to water cooled, see below). Air passing directly over the heat exchanger containing the refrigerant is used as the preferred heat rejection method (air cooled, see below).
In addition to this style of system we can offer water cooled chillers where a roof top cooling tower or closed loop heat rejection circuit is employed. Water is passed directly over the heat exchanger containing the refrigerant, this water is then superheated by the same and pumped to a suitable outlet. Once the water arrives at this outlet (a cooling tower for example), the water is sprayed / passed over a fan assembly and the heat consequently rejected into the atmosphere. The now sub-cooled water returns to the heat exchanger to start the process again.
A similar water cooled philosophy can be employed by DX systems ( outlined above ) but is less common than the CHW concept.
Fresh Air and Extraction systems are engineered as an additional add-on items interfaced with either the existing or new installation. As standard, the majority of light commercial systems only re-circulate the air within the area being served and do not offer fresh air input.
Fresh air is required to comply with CIBSE guidelines, building regulations and Health and Safety stipulations. If you do not have opening windows, you will need the addition of fresh air to comply with current legislation .There is much talk about the level of fresh air to be brought into a building and we at Air Options engineer systems around 8-12 L/S ( litres per second ), per person dependant upon the population of the office and of course budget.
Buildings constructed during the mid to late 1990’s are generally unsuitable to comply with modern legislation. This is due to increased occupancy levels & equipment loading from IT plant and improved lighting. Air Options can investigate the existing design and quote to upgrade the services to suit.
Environmentally friendly?
All of the systems outlined above employ refrigerant based gasses as a cooling medium . All systems comply with current legislation and no substandard manufacturers or materials are used which may contravene the standards laid down by the same legislation. We pride ourselves with this approach and have our own policy for you to review.
How can we help?
Air Options carry out all of the survey, design and installation working as to offer a complete ‘turn key’ package. Once the works are handed over, and operational, we produce extensive operation and maintenance (O and M) documentation and staff training if required.
Comfort cooling packages start from as little as a few thousand pounds and can in many cases dependant upon the complexity and size of the works be many hundreds of thousands of pounds. We have looked after many customers across the UK and at current service in excess of 300 clients. No matter what size the project, whether it be £10k or twenty times this, we pride ourselves that the end user will receive the same great service and support.
Once all of the works are complete we offer preventative maintenance agreements and full after sales support - supported by up to 36 month warranties.
Most importantly, all solutions are all engineered to comply with building regulations and Health and Safety guidelines.
Other relevant information can be found under the HVAC packages information.
Whatever your requirement, large or small, please do not hesitate to contact us where a member of our technical sales team will be happy to deal with any enquiry.
© copyright 2007, Air Options Limited