We’ve all experienced it.  You walk into a restaurant.  Maybe it’s your favourite, maybe it’s been recommended to you.  Nonetheless you love it.

 But there’s one problem:  your clothes and your hair stink after you leave it.  Disgusting.Nothing will ruin an evening more with friends or a loved one than having to go home to shower and change.

Even worse….  It’s a Friday or Saturday night there’s no chance of going home to change – so you AND your friends have to put up with it. 

There’s a misunderstanding out there that it may have to do with the type of cooking that’s taking place.  However it couldn’t be more wrong.

Without getting too technical this article will break down the most common issues/ symptoms and provide a solution to fix it.


So here we go:


What’s causing this issue?  One central problem:  Poor kitchen ventilation.  To understand the many issues surrounding this topic we must get into the fundamentals of Commercial Kitchen ventilation first:

Your Commercial Kitchen contains 3 items that make up your ventilation system

  1. The kitchen hood
  2. The kitchen exhaust fan connected to the hood
  3. The make-up air unit.


The hoods role is to capture and contain the products of combustion from the cooking process.  It acts like a dam to hold the cooking smells, grease, heat and steam until the kitchen exhaust fan has sucked it all up and discharged it away from the restaurant.


The kitchen exhaust fan typically sits on the roof of the restaurant and as described above pulls exhaust from the hood below to the outdoors and away from the space.

Seams like I addressed all the issues for Commercial Kitchens right?  Wrong.  We still have the make-up air unit where in my professional experience lays most of the issues


Why have a make-up air unit?  Think of it this way: a typical kitchen exhaust fan connected to a 10-14 foot hood would be removing about 2500-4000 cfm (cubic feet per minute).

To picture this, a typical condo in downtown Vancouver is say, 500 square feet with 8 foot floor to ceiling….   That means about every minute the entire air in your condo is being removed from your space!!!

Picture in 60 seconds no more air in your space-unless you open doors and windows to allow fresh air in to relieve the pressure.

This is the role of the make-up air unit:  to pump in fresh outdoor air and in the winter, and heat that air up so the occupants don’t freeze.  This is where many of the issues arise.  Below are symptoms of poor make-up air.


Symptom #1:  Door to restaurant is ‘heavy’

I love this one.  There’s a very famous restaurant in downtown Vancouver that had a ‘heavy’ entrance door to the restaurant.  The patrons entering it couldn’t open it, thus the solution was to hire a full time door attendant – at $50,000/ year!

After many years they discovered what the problem was:  no make-up air was being supplied to the restaurant.   Remember my analogy above about the Vancouver condo being exhausted every 60 seconds?  This in turn was causing a negative pressure within the restaurant causing the door to feel ‘heavy’

Symptom #2:  Drafty and cold in the seating area.

This is similar to Symptom #1 but with a slight difference:  no door man is needed but there is enough openings through doors and windows to allow make-up air to leak in.

This is more noticeable in winter: notice restaurant owners installing portable electric heaters around the seating area.  This is because the kitchen exhaust fan is pulling air directly from the outdoors, which could be freezing!

Symptom #3:  Your hair and clothes stink after dinner

Classic sign of poor make-up air.  This symptom is often blamed on the ethnicity of the cooking style but is not true (and I consider that ventilation discrimination! Lol).  Typically South east Asian are known for this issue.

Again it’s like my example above:  you’re removing a Vancouver condo from your restaurant every 60 seconds!…. Doors are closed….  It’s like trying to suck a watermelon through a straw: Ain’t gonna happen.

What does happen is the kitchen exhaust fan is overloaded and doesn’t remove the kitchen exhaust, smells and smoke from the restaurant.  You come out smelling like the food you ate :( yuk.


A thorough investigation of the entire Kitchen Ventilation System needs to take place by a qualified and experienced HVAC trade or engineer.

This is a service we provide and will in conjunction retain the services of an air balancer to test the systems performance.  Such as the kitchen exhaust fan exhaust and make-up air unit flow rate to make sure it is in compliance with ASHRAE std. 154.

If you have any questions about our blog, have an issue with your restaurant or just lonely give us a shout.  We will help you out with your Commercial Kitchen ventilation issues:

James Hicks P.Eng