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Duct cleaning - thermal design
A busy commercial kitchen generates an enormous amount of heat - from the cooking, the equipment, and the people - and under full load, that heat can make the kitchen an oppressive, even dangerous place to work. Staying cool under load is largely a matter of design: designing the ventilation and the space to carry the heat away. Here is how to design a kitchen that stays workable when the heat is on.
The short answer
A commercial kitchen produces a large heat load under full use - from the cooking appliances, the equipment, and the people - and designing it to stay cool means designing the ventilation and space to carry that heat away. The core is the extraction: sized and designed to remove the heat and the cooking effluent at the kitchen's peak load, not just its average, so it copes when the kitchen is busiest and hottest. That extraction needs matching make-up air - enough fresh air brought in to replace what is extracted, or the extraction is starved and cannot remove the heat (and the incoming air can itself be tempered or cooled to help). Where extraction and ventilation alone cannot keep the kitchen cool enough - as in many busy kitchens - active cooling or air conditioning is designed in to remove the remaining heat. And the layout helps: positioning heat sources, providing air movement, and not trapping heat. So designing a kitchen to stay cool under load is about sizing the ventilation for the peak heat, supplying the make-up air it needs, and adding cooling where required - so the kitchen stays workable when it is busiest, rather than becoming unbearable.
The heat load under full use
Designing a kitchen to stay cool starts with understanding the heat it has to deal with - which, under full load, is considerable. A busy commercial kitchen generates heat from several sources at once: the cooking appliances (ovens, ranges, fryers, grills) radiating and convecting heat; other equipment (dishwashers, hot-holding, refrigeration rejecting heat); and the people working hard in the space. Together, at peak load - a full service, all the equipment running, the kitchen busy - these produce a large heat load concentrated in the space, which can drive the temperature up to oppressive levels if not carried away.
This heat load is what the design has to handle, and the key point is that it has to be handled at the peak, not just the average. A kitchen designed for its average heat load will be overwhelmed at its busiest, hottest times - exactly when staying cool matters most. So the design has to reckon with the peak heat load: the maximum heat the kitchen generates when fully loaded, which is when the cooling and ventilation are most needed and most tested. Understanding where the heat comes from, and how much there is at peak, is the basis for designing to remove it. A kitchen is inherently a hot environment because of all these heat sources, so staying cool is not about eliminating the heat - which the cooking inherently produces - but about carrying it away as fast as it is generated, at the peak load. That is what the design has to achieve.
Extraction sized for the peak
The core of keeping a kitchen cool under load is the extraction - and specifically, extraction sized and designed to remove the heat and cooking effluent at the kitchen's peak load. The extraction system, drawing the hot, grease-laden air up through the canopy and out, is the main way the heat is carried away from the cooking. If it is sized for the peak heat load, it can remove the heat as fast as the busy kitchen generates it, keeping the temperature down; if it is undersized - designed for less than the peak - it cannot keep up when the kitchen is fully loaded, so the heat builds up and the kitchen overheats at its busiest.
So designing for cool operation means sizing the extraction to the peak heat load, so it has the capacity to carry away the maximum heat the kitchen produces. This is a fundamental design decision: the extraction's capacity sets the ceiling on how much heat can be removed, so it must be enough for the peak. It is also why keeping the extraction performing matters for staying cool - an extraction that has lost capacity, through grease build-up clogging the ducts and reducing the airflow, cannot remove the heat it was designed to, so a kitchen with a clogged extraction will run hotter under load than one with a clean, full-capacity system. So the extraction is central both in design (sized for the peak) and in operation (kept clean and performing), because it is the main means of carrying the heat away. A kitchen stays cool under load largely because its extraction can remove the peak heat - which depends on it being sized right and kept working.
Make-up air and cooling
Extraction alone is not enough - it needs matching make-up air, and often active cooling too. The make-up air is essential because the extraction can only remove air as fast as it is replaced: if enough fresh make-up air is not supplied to replace what the extraction removes, the extraction is starved and cannot carry away the heat, however well it is sized. So designing for cool operation means providing make-up air matched to the extraction, so the extraction can work at full capacity. And the make-up air itself can help with the heat: supplying tempered or cooled make-up air - fresh air brought in at a comfortable temperature rather than hot outdoor air - directly helps keep the kitchen cool, bringing in cool air to replace the hot air extracted.
But in many busy kitchens, extraction and make-up air alone cannot keep the space cool enough - the heat load is too great to be handled by air movement alone, especially in warm weather. Where that is the case, active cooling or air conditioning is designed in, to remove the heat that the ventilation cannot, and to keep the kitchen at a workable temperature. So the design combines extraction (removing the heat and effluent at the source), make-up air (feeding the extraction and bringing in cool air), and cooling (removing the remaining heat where ventilation alone falls short). These work together: the extraction and make-up air carry away much of the heat, and the cooling handles what is left, so the kitchen stays cool under load. Designing all three appropriately for the kitchen's peak heat load is what achieves a kitchen that stays workable when busy, rather than one that relies on extraction alone and overheats when the load is highest.
Layout and keeping it working
Alongside the ventilation and cooling, the layout of the kitchen helps it stay cool under load. Positioning the heat-generating equipment sensibly - grouping it under the extraction where the heat is captured, not spreading it where heat escapes into the working space - helps the extraction capture the heat at source. Providing air movement through the space, and not creating trapped, unventilated hot spots, keeps the air from stagnating and heating up. And considering the flow of people and the working areas, so that the hottest zones are managed and staff are not stuck in the worst of the heat, helps keep the working environment tolerable. So the layout supports the ventilation and cooling in keeping the kitchen workable.
Finally, staying cool under load depends not just on the design but on keeping the systems working - because a well-designed system that is not maintained loses its capacity. The extraction, in particular, must be kept clean: grease build-up clogs the ducts, reduces the airflow, and cuts the extraction's capacity to remove heat, so a kitchen designed to stay cool will run hotter than intended if its extraction is allowed to clog. Keeping the extraction cleaned maintains the heat-removal capacity the design provided. So designing a kitchen to stay cool under load is completed by maintaining it: the design provides the capacity - extraction sized for the peak, make-up air, cooling, sensible layout - and the maintenance, especially keeping the extraction clean, preserves that capacity so the kitchen actually stays cool in use. Design for the peak heat, and keep the systems clean and working, and the kitchen stays workable when the load is highest.
The takeaway
A commercial kitchen generates a large heat load under full use - from the cooking, the equipment and the people - and designing it to stay cool means designing the ventilation and space to carry that heat away at the peak load, not just the average. The core is the extraction, sized to remove the heat and effluent at the kitchen's busiest, hottest times. It needs matching make-up air, or it is starved and cannot remove the heat - and that make-up air can be tempered or cooled to help. And where extraction and ventilation alone cannot keep the kitchen cool enough, as in many busy kitchens, active cooling is designed in to remove the remaining heat. The layout helps too, positioning heat sources under the extraction and providing air movement.
So the design combines extraction sized for the peak, make-up air to feed it and cool the space, and cooling where needed - working together to keep the kitchen workable when busy. And it is completed by maintenance, because a well-designed system loses its capacity if not kept working: the extraction especially must be kept clean, since grease build-up clogs the ducts and cuts its heat-removal capacity, so a kitchen runs hotter than designed if its extraction is allowed to clog. So design for the peak heat load - extraction, make-up air, cooling, layout - and keep the systems, above all the extraction, clean and working, and the kitchen stays cool under load rather than becoming unbearable when the heat is on.
Questions
Because it generates a large heat load from several sources at once: the cooking appliances radiating and convecting heat, other equipment (dishwashers, hot-holding, refrigeration rejecting heat), and the people working hard. Under full load, at a busy service, these produce a large amount of heat concentrated in the space, which drives the temperature up if it is not carried away as fast as it is generated.
By designing the ventilation and space to carry the heat away at the peak load: extraction sized to remove the heat and effluent when the kitchen is busiest; make-up air to feed the extraction and bring in cool air; active cooling where extraction alone cannot cope; and a layout that positions heat sources under the extraction and provides air movement. All sized for the peak heat, not just the average.
Because a kitchen designed for its average heat load will be overwhelmed at its busiest, hottest times - exactly when staying cool matters most. The extraction's capacity sets the ceiling on how much heat can be removed, so it must be enough for the maximum heat the fully-loaded kitchen produces, or it cannot keep up when the load is highest and the kitchen overheats.
Because the extraction can only remove air as fast as it is replaced - if enough make-up air is not supplied, the extraction is starved and cannot carry away the heat, however well sized. So make-up air matched to the extraction lets it work at full capacity. And the make-up air can be tempered or cooled to help directly, bringing in cool air to replace the hot air extracted.
In many busy kitchens, extraction and make-up air alone cannot keep the space cool enough - the heat load is too great to handle by air movement alone, especially in warm weather. Where that is the case, active cooling or air conditioning is designed in to remove the remaining heat. The extraction and make-up air carry away much of the heat, and the cooling handles what is left.
Yes - a well-designed system loses its capacity if not maintained. Grease build-up clogs the extraction ducts, reduces the airflow, and cuts the capacity to remove heat, so a kitchen designed to stay cool will run hotter than intended if its extraction is allowed to clog. Keeping the extraction cleaned preserves the heat-removal capacity the design provided, so the kitchen actually stays cool in use.
A kitchen stays cool because its extraction removes the heat - but grease build-up cuts that capacity, so it runs hotter. Our duct cleaning keeps the extraction at full capacity, carrying the heat away as designed.
