Warm hats, gloves, scarves and coats are nothing new for people to wear during the winter. It’s winter, so we deal with it, right? However, what if people are consistently wearing this winter apparel in the office?
A recent article published on January 10th in the Minneapolis Star Tribune by Philip Marcelo of The Associated Press addressed this very issue. Office dwellers throughout the country are layering up to combat the chilly temps in their buildings.
This issue of thermal comfort affects us all, and in different ways. Air temperature was the primary area of focus in the article. This makes sense, since it’s the one factor that most people can relate to immediately. What is the air temperature in the work space? We know when it’s cold because we can feel it.
What other factors affect thermal comfort? Along with air temperature, the other three environmental factors are humidity, air velocity, and mean radian temperature. A mechanical engineer like myself, and others at Gausman & Moore, can change these four factors in the indoor environment to achieve this elusive thermal comfort. Other factors can include conduction, convection, radiation and evaporation into a heat balance equation, but that gets complicated.
There are four other non-environmental factors that building designers cannot control. This includes clothing that people wear, the metabolic rate, gender, and the age of the occupants. The question becomes, is anyone comfortable in their office environment?
The word “elusive” is applicable when discussing thermal comfort because ASHRAE standard 55 says that a space meets the thermal comfort standard when only 80 percent of the occupants consider themselves comfortable. The previous day’s office poll could comprise different people from tomorrow’s poll. So, what is the answer? How do we as mechanical engineers design a building for occupant comfort?
The author of the newspaper article was on the right track with individual comfort control, but I would like to offer a few more suggestions on how the central heating system can work with individual control possibilities. Of course, any project will have competing factors along the way that determine the outcome.
The goals that take priority in a building project affect the options on how a building delivers thermal comfort. If thermal comfort is a priority, then things like underfloor air distribution systems with individual adjustable diffusers, radiant heating panels or in-floor heating with thermostat control, ceiling fans, or even operable windows depending on the climate can help users be able to control their thermal environment. Not that these types of systems cost more, but if the project budget takes priority over all else, this limits the opportunity for individual control. My suggestion is to invest in design and stretch the budget to make sure individual comfort control is a priority.
As the head of the mechanical department at Gausman & Moore, I oversee the design of many building types across many climate zones. Our exceptional mechanical engineers make every day fun as we tackle a variety of project types that keep us on our toes. The important part is making sure everyone’s toes stay warm.
By Dan Fox – Principal, Mechanical Department Head