Laboratories are well known to consume massive amounts of energy, and this is often directly correlated to the number of fume hoods in operation. As a result, labs can often times consume 5 to 10 times more energy than other buildings. So how can you lower your energy consumption and reduce your energy bill?
Fume Hood Costs
Let's start by understanding just how much energy fume hoods consume. Consider this, one fume hood will consume as much energy as a single-family home in a 24-hour period. This energy consumption is due to the ventilation used to pull chemical vapors out of the room. According to a Harvard study ventilation accounts for 44% of energy consumption in labs. In 2015 the same study estimated that each fume hood cost a lab $4,459 in energy costs per year. That is a significant amount money. By changing just a few things, you can reduce your fume hoods energy consumption and lower your labs operating costs.
Ways To Save
Constant Volume Vs Variable Air Volume Fume Hoods
The first step for any lab to save a considerable amount of money is to understand whether they have a Constant Air Volume (CAV) System or a Variable Air Volume (VAV) System. Making the switch from CAV to VAV can save thousands! In fact, in some cases labs have reduced their energy consumption by as much as 75%.
CAV systems constantly pull the same volume of air out of the room through the hood exhaust whether it is in use or not. The problem is that these systems are constantly pulling conditioned (cooled or heated) indoor air outside. This requires the HVAC system to run constantly to replace that exhausted air with more conditioned air for the space. This creates an energy consumption nightmare! CAV kept lab safe and were originally a good strategy before fume hoods had sensors that were able to detect whether or not they were in use.
VAV systems on the other hand reduce the exhaust rate based on whether the hood is in use. When systems are not in use the exhaust rate drops dramatically which is why the energy savings can be so dramatic.
Lower The Sash
(This requires you have a VAV system already installed) This strategy was pulled from a Harvard study that found that much of the operating costs associated with fume hoods was because sash doors were left open when not in use. By making a competition of lowering the Sash when not in use, Harvard was able to reduce the ventilation rates in the lab. This simple change resulted in a savings in excess of $200,000 per year.
Important Note: During the study Harvard found that automatic fume hood sash closers were generally not liked by scientists. They often closed at inopportune times and beeped often. Some people disabled the sensors and jammed pencils into the buzzers to prevent them from going off.
Optimize Ventilation Rates
Based on the type of fume hood and the types of chemicals being used, your labs ventilation rates may be able to be improved. Consider having an expert out to analyze current ventilation rates and adjust your fume hoods appropriately. This is especially important if you have an older lab. Newer technology and changes in lab standards can help you lower these ventilation rates significantly.
Decommission Fume Hoods Not In Use
As occupancy changes or the number of fume hoods needed is reduced, consider de-commissioning the unused units. This will ensure air is no longer flowing through the hood which will reduce the strain you put on HVAC system and save you money.