We design and install treated fresh air systems that deliver the ventilation the code requires without handing the building a humidity problem.
Every occupied building has to bring in outside air. In Jeddah and along the Red Sea coast that air arrives warm and very wet, and most of the energy needed to condition it goes into removing moisture rather than lowering temperature. Inland, in Riyadh, the balance is the other way round. The same unit selection cannot be correct in both places.
This is where fresh air systems most often go wrong. A unit sized on sensible cooling load alone delivers air that is cool and still wet. Room humidity climbs, condensation forms on diffusers and chilled water pipework, and within a year or two there is mould in the ductwork and a smell nobody can locate. The air conditioning is blamed, and the air conditioning is not the fault.
Green Flash designs fresh air provision from the psychrometrics for the actual site, sets the ventilation rate against ASHRAE 62.1 and the Saudi Building Code, and coordinates it with the HVAC and chilled water systems serving the same spaces rather than treating it as a separate duct run added later.
TFA and dedicated outdoor air units that take the air down past its dew point to strip moisture out, then reheat it to a sensible supply temperature. Delivering dry air centrally lets the room units handle sensible load only, which is what they are good at, and it keeps humidity under control across the whole floor rather than room by room.
Plate heat exchangers and thermal wheels that take heat, and with the right wheel moisture too, out of the air being thrown away and use it to pre treat the air coming in. The gap between inside and outside is large here for most of the year, which is exactly the condition that makes recovery pay back faster than it does in a temperate climate.
Staged filtration with an accessible pre filter ahead of the fine filter, sized so the dust load does not collapse airflow between service visits. Filter grade, filter area and how easily a technician can change them matter more here than the specification sheet suggests, because a blocked filter quietly starves the building of the ventilation it was designed for.
Toilet, kitchen and car park extract with CO monitoring where it is required, and stair and lobby pressurisation interfaced with the fire alarm system. Supply without matching extract simply pressurises the building and pushes conditioned air out through every gap in the facade.
We calculate the required rate from occupancy and floor area for each space type, and apply realistic diversity rather than assuming every seat is filled at once. Over ventilating is not a safety margin, it is a permanent running cost and, in a humid climate, a latent load the plant has to carry all day.
The unit is selected against the design condition for that location, coastal or inland, with the supply dew point set so the space holds the humidity the client needs. Reheat strategy is decided here, because reheating with new energy when recovered heat is available is the most common avoidable waste in a fresh air system.
Carbon dioxide sensing in spaces with variable occupancy so the system modulates to the people actually in the room. In meeting rooms, lecture spaces, retail and prayer halls this is usually the single largest saving available, and it costs a sensor and a control loop rather than new plant.
Measured airflow at every terminal, recorded and handed over, with filter pressure drop and unit performance logged at commissioning so there is a reference to compare against later. An unbalanced fresh air system looks identical to a balanced one until somebody complains.
Green Flash Engineering and Contracting has completed over 21 major projects across Saudi Arabia, supported by teams operating in Jeddah, Riyadh, Yanbu, Rabigh and King Abdullah Economic City. Ventilation and air quality run through our healthcare and pharmaceutical work, where pressure relationships between rooms carry clinical weight, and through our industrial and retail and hospitality projects.
We are an electromechanical contractor rather than a ventilation supplier, so the fresh air system, the chilled water systems serving it, the VRF terminal units and the controls are designed and commissioned by the same team. Where the building also needs refrigeration or cold storage, that comes under the same contract.
Once a system is running, the ventilation strategy is usually the fastest place to find savings. That work is set out on our energy optimisation page.
It depends on the space type and the occupancy, not on the floor area alone. ASHRAE 62.1 sets a rate per person plus a rate per square metre for each category of space, and the Saudi Building Code adopts the same basis. An office, a classroom, a restaurant and a workshop all land on very different numbers. We calculate it per space and show the working.
A mixed air AHU can handle it on smaller systems. On anything with variable occupancy, or where humidity has to be held, a dedicated treated fresh air unit is usually the better answer, because it lets you dry the outside air properly at one point instead of asking every terminal unit to fight moisture it was not selected for.
In most cases yes, and more so than people expect. The temperature and humidity difference between the air you are throwing away and the air you are drawing in is large for most of the year, and that difference is what recovery monetises. We size it and show the payback rather than fitting it by default, and on a building with low fresh air volumes we will tell you it is not worth it.
Yes, and it starts with measurement rather than equipment. We log temperature, humidity and airflow, check the supply and extract balance, inspect the coils, drains and ductwork, and find whether the problem is selection, control, balance or maintenance. Those four have very different costs to put right, so identifying which one it is comes first.
Send the layout and what each space is used for, or the complaint you are getting. We will come back with the ventilation rate, the unit selection and whether recovery pays on your building.
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