Occupant comfort is the driving force in building design, it is the reason buildings have HVAC systems and insulation. BioPCMTM makes spaces more comfortable by stabilizing surface temperatures and effecting the mean radiant and air temperatures of the thermal zones where it is installed.
The financial value of comfort enhancement is typically greater than what is possible from energy or maintenance savings. In most buildings the annual cost per square foot to pay employees far exceeds any other cost. Enhanced comfort increases productivity and even a small increase in productivity can provide significant cost benefits. Numerous studies have shown that productivity can be correlated with temperature. When bioPCM is installed, comfort conditions are kept within the optimal productivity zone a greater percentage of time.
- According to the EIA the average annual energy cost per square foot for commercial buildings is $1.19.
- According to ASHRAE the average annual cost per square foot for HVAC maintenance is $0.50.
- The average square feet per person for an open office is 220, with a median annual income of $40,000 the average cost per square foot for salaries paid to employees is $181.82.
The cost of employee salaries is 108 times greater than that of the combined cost of total energy and HVAC maintenance. An increase in employee productivity of 1 percent creates a value of $1.82 per square foot. If you add up total energy and HVAC maintenance costs you have $1.69 per square foot. The conclusion is that a 1% increase in productivity creates more value than would be created by totally eliminating the energy and HVAC maintenance costs of the building. The bottom-line; enhanced comfort increases productivity, and productivity is the most valuable thing in buildings.
Throughout the last few decades, researchers have been exploring ways to predict the thermal sensation of people in their environment based on the thermal, environmental, physiological and psychological variables that influence thermal comfort. From the research done, mathematical models that simulate occupants' thermal response to their environment have been developed and included in EnergyPlus simulation software. The most notable models have been developed by P.O. Fanger, because it was the first one developed (1967 and then in 1972), and set the stage for the other models. Fanger proposed that optimal conditions for thermal comfort were expressed by the regression line of skin temperature and sweat rate on metabolic rate in data from these experiments. In this way an expression for optimal thermal comfort can be deduced from the metabolic rate, clothing insulation and environmental conditions. The final equation for optimal thermal comfort is fairly complex and need not concern us here. Fanger has solved the equations by computer and presented the results in the form of diagrams from which optimal comfort conditions can be read given a knowledge of metabolic rate and clothing insulation. ASHRAE 55 comfort standards are based on the original work of Fanger and use the premise that people would dynamically change their clothing based on the season, (ie sweater in winter, t shirt in summer) and count hours of modeled discomfort. There are other comfort models, and the two mentioned in this rudimentary explanation are significantly more detailed than highlighted here. The main point is bioPCM changes surface temperatures and air temperatures causing buildings to be more comfortable in measurable and scientific ways.