Recently, our firm was contacted to assist with an HVAC evaluation for a dormitory at a university in an adjoining state. The building was constructed in the early 1960s when cooling equipment was a new concept, generally rugged and durable, but unsophisticated. Controls were inaccurate and modulation was limited. Energy was cheap and humidity was not of concern. Dormitories were basic and one step above containment cells – a place for students to sleep, and maybe study if it was quiet. Social interaction occurred in the TV room or at the student center. Dining was at a campus cafeteria/dining facility. Having a cool dorm room was unheard of, so any temperature below 85°F was outstanding!
Knowledge and understanding of how to control building air pressure in mid-and high-rise buildings was just beginning to develop in the 1960s. Winter heating conditions opposed to summer cooling conditions. In the winter, a stack or chimney effect caused the warm, low-density air to rise and heat the upper-level floors; at the same time cold, dense air was infiltrating through the lowest level. In the summer, the reverse occurred. The pressure difference across the building envelope caused considerable temperature variance from floor to floor. Because control of building pressurization was unknown, make-up air was initiated through operable windows or intake louvers connected to air-handling equipment. Exhaust fans had only two settings, on or off. They usually ran continuously day and night and were arranged through the basic time-clock operation. Dorms of the 1960s were designed for longevity, and interior changes were not thought necessary except for painting.
Advancing to the early 1980s, interior comfort and privacy was expected in dorms, as was increased natural light, study areas and snack areas with cooking surfaces. The 1960’s dormitories were incapable of accepting these changes without extensive building envelope updates. The needed changes were very difficult and expensive, so they were typically ignored. Beginning in the 1990s, the technology age emerged and the need for consistent indoor air quality was required. It was hopeful that the 1960’s buildings could be reused and adapted to the new expectations. This is when the problems started. Tightening building envelopes properly was difficult. Insulating the buildings required improved glazing, exterior wall insulation, and vapor barriers. Since building sciences were new, especially when it came to securing building envelopes, there were varying opinions about how to seal and insulate buildings.
The 1960’s dormitory we were tasked with evaluating resulted in humidity issues. The improved building envelope changed the location of the dewpoint causing water to condense in the walls during certain conditions. The HVAC system was not consistently bringing in the required make-up air to positively pressurize the building; nor did it consistently dehumidify the air to limit moisture inside the building. These factors added up to mold growth inside the building. As with most problems, the causes were multi-faceted and required multiple solutions. The aggregate of the solutions was deemed cost-prohibitive and the decision was made to replace the building.
If all parameters of the building had been considered during the periodic improvements, the moisture/mold problem may have been avoided. The improvements might have cost more initially, but the end result would have been a building that survived with a healthy indoor environment. Instead, the building life was cut short.