Newman Vertical Campus

Thermal Comfort

Ducts
Photo credit: U.S. Department of Energy


The heating, ventilation and air conditioning systems in large commercial buildings must operate efficiently to maximize energy savings and thermal comfort. Many common HVAC problems have simple solutions.

In most buildings, air circulates through channels called ducts. Ducts are generally made of lightweight metal and may use other material for connections and insulation. These can be within walls or outwardly visible. Frequently, they are above ceilings or in crawl spaces. It is important for property owners to inspect ducts regularly, including upon first installation and after 10 years of use. Improper conditions in ducts can lead to energy loss and higher energy costs. (More about minimizing energy loss in ducts.)

Duct quality and connections

A quick inspection of ducts can often identify holes and bad connections. On average, 20% of transmitted air is lost as a result of improper duct work. Mastic sealant and metal tape are simple solutions for these issues. Some supply ducts may benefit from insulation, depending on external temperatures and intermediate spaces. (More about sealing and insulating ducts.)

Cleaning ducts and vents

Ducts and vents should be cleaned internally. Many ducts can be cleaned with long-hosed vacuums. Others many require removal and reinstallation. Vents should be cleared of any obstructions, including furniture. Faulty, blocked or unclean ducts or vents can prevent air flow and create temperature backups, causing more maintenance problems and raising energy costs for unconnected rooms. Rooms are most efficient when they have both input and output vents; in other words, supply air and return air.

Most ducts have filters which should be checked regularly and replaced as recommended by the manufacturer. Neglected filters are a common problem, and blockage will overwork ventilation systems and increase energy costs. In addition, unclean filters will negatively affect indoor air quality, with potential health consequences.

Boilers and furnaces

Most buildings use boilers or furnaces as the source of their heating. These should be professionally assessed to determine if they are properly sized. If a boiler or furnace is proportionally too large for its space, it will be inefficient and frequently cycle on and off, making consistent heating difficult. If the equipment is undersized, it will be overworked, which would result in increased energy costs. Many boilers and furnaces are available in Energy Star models.

Windows and doors

Windows and doors are an essential part of the heating system and should be sealed carefully into their surrounding spaces. They can also be chosen for their insulation values. Windows should be positioned and treated to maximize winter light and keep out summer light. (More about window treatments.) (More about daylighting.) Simultaneously, correct window usage can decrease summer cooling costs. Where windows have to be opened during cold months for ventilation or cooling, the building's heating and ventilation systems need to be addressed. (Seasonal heating tips.) Direct outside air is difficult to filter and will affect indoor air quality.

Programmable thermostats

Programmable thermostats are an easy way to maximize heating and cooling efficiency. These have internal timers which can be set to activate during certain hours of the day and even certain days of the week. Offices spaces which are unoccupied on nights or weekends can greatly benefit from these settings. Installing automatic thermostats reduces labor costs and reduces reliance upon individual tenant activity. (More about programmable thermostats.) (More about thermostats and control systems.)