73 FAHRENHEIT IN MY OFFICE, AND I’M COLD.

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Like everybody in these office towers, we have central heating / air conditioning. For the winter season, the temperature is set at 73 Fahrenheit.  After many complaints, we got our system audited.  We were surprised to learn that it was in top shape.  The inspection determined that the temperature is controlled to within one degree Fahrenheit of the set point at all times.  Does this mean that we are a bunch of crybabies who have nothing better to do than complain?  Of course not! So why do we feel cold?

You must understand that thermal comfort is very personal and depends on individual body metabolism.  Furthermore, many outside conditions affect the way you perceive thermal comfort.  The most common are :

  • Air temperature
  • Relative humidity
  • Radiant temperature
  • Air movement
  • Air temperature stratification
  • Workstation layout
  • Level of physical activity
  • Clothing

AIR TEMPERATURE
For most people, this is the only factor affecting thermal comfort that we can control.  That is the reason for the room thermostat.

RELATIVE HUMIDITY
With low relative humidity, the perceived temperature is lower than the actual room temperature.  We find that most office towers HVAC system control relative humidity adequately, if not than a personal humidifier may be required.

RADIANT TEMPERATURE
All objects, all people and all surfaces that surround you radiate infrared waves and contribute, to your perception of thermal comfort. The more your surrounding radiates infrared heat, the warmer you feel regardless of the actual temperature.  Outside, the winter does not feel so cold because of the infrared warmth of the rays of the sun.  On the other hand, if you radiate more infrared energy than your metabolism can comfortably produce, you feel cold.

AIR MOVEMENT
Moving air temperature is always perceived as colder than still air. Wind chill factor is a reality at all temperatures.

AIR TEMPERATURE  STRATIFICATION
Hot air being lighter than cold air, it goes up to the ceiling.  It is not uncommon to see as much as a 10o Fahrenheitdifference between floor and ceiling temperatures.

WORKSTATION LAYOUT
The configuration of your workstation and its location are determining factors of your thermal comfort as they greatly influence the other factors.  Furthermore, the space under your desk is a special case, it is almost a closed off area.  It is located at floor level where the air temperature is the coldest, and to make things worst, it is sealed off from most sources of radiant heat, making it the undisputed coldest spot in the office.  Therefore people say they are cold, because they have cold feet.

LEVEL OF PHYSICAL ACTIVITY
Your job description requires a prolonged or constant presence at your workstation.  Because of the sedentary nature of your work, you feel cold sooner and more intensely than other workers that move around and do more physical work than you do.

CLOTHING
Regardless of the dress code at your office or of the prevailing fashion, when we talk of thermal comfort, the clothes you wear is only a layer of insulation with which you cover yourself to protect you from the cold.

All of these factors influence the way we perceive thermal comfort.  Obviously the HVAC system is not the source of all office worker thermal discomfort.  The solution is somewhere else: for example, people with warm feet do not complain much; maybe warm feet are part of the solution.  Many people think so and their solution is the standby blast heater.  Unfortunately, there are major downsides to that easy solution, the most serious being:

  • High energy use
  • Hot air migration
  • Cumbersome
  • High noise level
  • Fire hazard

HIGH ENERGY USE
The average standby blast heater uses between 1200 and 1500 Watts/hr.  This high-energy consumption disrupts and overloads the electrical circuits, opening the breakers and causing local power failure.  Electricians are required to get back on line and fix the problem.  Often times power failures result in loss of data and sometimes more serious computer and equipment problems.

HOT AIR MIGRATION
The standby blast heaters push a lot of hot air. Most of it leaves your workstation and heats up your coworkers that are not cold at all.  The hot air from the blast heater may also influence the room temperature settings when the thermostat is close to your workstation.

CUMBERSOME
The standby blast heaters are typically installed on the floor under your desk and are always in the way.

HIGH NOISE LEVEL
Standby blast heaters are very noisy.

FIRE HAZARD
Standby blast heaters installed under the desk are unstable and can be easily knocked down.  Flammable material is often present and constitutes a fire hazard.

For all these reasons and many more, the use of standby blast heaters are outlawed in many offices, so what can we do?

With the standby blast heater, it is difficult – almost impossible – to increase the comfort level of one worker without affecting the comfort of all the other workers.  The only thing left that has the potential to increase the thermal comfort of the office worker is radiant heat.  Infrared rays travel thru the air to directly warm up solid objects and people; not the air.  Adding a source of radiant heat under the desk seems promising.  Our testing has concluded that installing a source of radiant heat under the desk is a very practical way of warming up that space noiselessly.   Lower body is kept comfortably warm for less than 80 Watts/hr.   Furthermore, comes summertime when air conditioning kicks in, do not expect people to stop being cold.  In the summer time, under the desk it is as cold as ever but people wear summer clothes and standby blast heaters are even less welcomed than in the winter months.   That is why adding a source of radiant heat under the desk with its low energy consumption and silent operation is such a great idea even in summer.