As many HVAC and Energy Conservation professionals can tell you – even though ventilation is in the code – there are many commercial buildings that are not keeping their mechanical ventilation operable. Dampers meant to be functional are screwed shut and economizers are left to wither.
As someone that has been in the energy conservation field for over a baker’s-dozen years, however, I can tell you that us energy wonks know that mechanical ventilation is the key to not only efficiency (free cooling* anyone?), but health. And now that the world is in a healthcare crisis to beat all healthcare crises, it’s time to review what ventilating right can do for you.
First, for the sake of argument, why ventilate at all? Clearly, heating and cooling is a manufactured system that seemingly provides plenty of air movement to condition to comfortable temperatures during the summer and winter months. If correctly filtered, the scent of that air conditioning can smell as fresh as newly fallen snow. Depending on how and when your building was constructed, however, that conditioned air can be deceiving.
As commercial buildings went from mostly wood, masonry and single pane windows, to steel-stud framing and triple pane glazing, the HVAC industry-powers-that-be started recommending implementation of mechanical ventilation.
Air grows stale. And if the building is too tight, it can lead to sick building syndrome. This took some time to identify – and it is still a problem that many office workers have been dealing with – like the Cheshire cat, it exists invisibly, undiagnosed.
Bringing in outside air, but tempering it first, eliminates – or at least mitigates – the problem with enclosed spaces that have too many people and not enough conditioning to cover the added humidity and carbon dioxide created by humans working or playing in close proximity to each other. Just circulating air in a closed-loop system will not create fresh oxygen and lower humidity. You need Outside Air Systems (OAS) – sometimes just a damper and an economizer on your roof top unit – to freshen up the place.
There are many equipment options, depending on the size, scope and system being used. A mechanical engineer or HVAC designer has all the calculations to help businesses choose how much air the building needs per person. (Consult your contractor, as this is above my pay grade).
But how does this relate to today and the crisis we face from the declared pandemic?
To answer this, look at how hospitals use mechanical ventilation to contain diseases, for example. An infectious disease ward needs to ventilate and actually over-pressurize rooms where viruses have to be contained. To illustrate:
Now, as I’ve written previously, a correctly conditioned office space actually leads to better productivity. It also means less people calling in sick due to airborne illness and sick building syndrome. Think what it can do in this time of pandemic.
A modest proposal:
- Create failsafe ventilation systems with the wealth of new CO2 and temperature sensors to operate when the air grows stale. Smart buildings are the key to better health, not just efficiency.
- Filter the outside air coming in to prevent any outdoor pollutants from permeating the space as well.
- Exhaust the inside air to the exterior to eliminate stale air.
- Use ERV/HRV technology to pre-temper the air as needed, depending on the climate and season.
Perhaps this sounds elementary, but again, some older buildings have let their systems fail to provide this basic formula.
As these tough times illustrate, we are all in this together. Let’s takes lemons and make a lemonade of healthy, well-ventilated, environments.
Mary English has been working in sustainable construction and building science for over thirteen years. She has worked with multiple designers and builders in the Kansas City region testing and consulting on best practices from building envelope to HVAC. She currently serves as the Committee Chair for the USGBC Central Plains Programs Committee.