Wednesday, February 19, 2014

DOE Wants to Help You Improve Your Commercial HVAC Systems Efficiency

Our AEE chapter meeting in January was the kick off meeting for the George Washington University’s new student chapter. The speaker was Ms. Karen Butler, EPA’s National Manager Commercial Building Design Initiative – Energy Star.

As you might imagine, EPA’s interest in efficient building design and operation is to promote the reduction of energy consumption and the avoidance of the pollution that results from producing the unnecessary energy. The ‘Target Finder Tool’ is part of the EPA’s ‘Energy Star Portfolio’ a collection of no cost, on line tools that can help you design more energy efficient buildings, track their performance and compare them to similar, energy efficient commercial air conditioners, facilities.

Wednesday, February 12, 2014

Variable Frequency Drives in Single Zone Rooftop HVAC Units as Installed by Commercial HVAC Contractors

It is our understanding that VFDs are now required in single zone units in California and that other states may follow. ASHRAE standard 90.1-2010 requires VFDs in single zone, direct expansion (DX) units with cooling capacities of greater than 9.1 tons. If you are not familiar with the term, DX units are your typical package rooftop units which have internal compressors. ASHRAE standard 18931-2009 also requires VFDs in single zone DX units with cooling capacities of greater than 9.1 tons and, in addition, two stages of cooling in units with cooling capacities of greater than 5.4 tons. This may provide additional savings because having multiple stages may allow you to use lower blower speeds than with single stage, on/off, compressors. You may check with your local code authority to see if these standards have been adopted by your jurisdiction, and/or consult with commercial HVAC specialists

As with any equipment modification, there are a few things you need to be aware of when having qualified commercial HVAC contractors install VFDs on single zone units. From the service contractors’ viewpoint, the most immediate issue is to ensure that the low-speed setting moves enough air across the coil in the cooling mode to prevent “flood back,” a condition where the refrigerant does not absorb enough heat and returns to the compressor in liquid form. In severe cases, flood back can damage even the newest scroll compressors. Concern for this may be the reason that both ASHRAE standards will accept a low setting of two-thirds of full speed. Since even slower speeds may work in many applications and provide greater savings, the safest approach would be to check each unit individually. Existing problems external to the unit such as undersized or restricted duct work, closed diffusers or dampers, leaks between the supply and return ducts and other issues may not allow for sufficient air flow when the blower speed is reduced. Insufficient air flow would also be a problem in the heating mode because it may result in the short cycling of the safety devices, overheating of the heat exchangers, and possibly an increase in the air temperature above the safe design temperature for that equipment.

Thursday, February 6, 2014

Benefits of HVAC Maintenance for Businesses

The recent American cold wave has affected a lot of American cities. The record low temperatures and high levels of snowfall has affected education, services and transportation. The extreme weather reminded a lot of communities of the importance of heat in people’s lives.
Heat is usually provided to homes and buildings by furnaces and similar heating systems. Like a lot of other machines, however, furnaces tend to malfunction after a certain period of time. This is the reason why HVAC maintenance is required for both commercial and residential HVAC systems.
A reduced risk of HVAC failure when it is needed most is one of the greatest perks companies and families will receive out of regular HVAC maintenance. Businesses located in cold places cannot function properly if the heater malfunctions, which can cause these businesses to lose profits. A well-maintained heater prevents that unfortunate circumstance from happening.
Another positive that businesses can obtain from regular HVAC maintenance is a better heater. A regularly maintained heater can run much more efficiently, which means less expenditures for the company. A well-maintained heater can help businesses profit.

Thirdly, heater maintenance can have an effect on air quality. Dirty heaters equate to poor air quality that is detrimental to employees allergic to dust. Regular HVAC maintenance helps employees maintain good health and perform much better at work, which results in a better output for the company. 

Air Conditioners for Human Comfort & Efficiency

Air conditioners are a must-have among many office spaces and commercial buildings. This is especially true of areas whose temperatures are too high for comfort.

An article on Bright Hub Engineering lists common sources of rising temperatures. The sun is the major cause of heat generation inside the room of an office or a building. Sun rays enter the room through the roof, walls, and windows of the building which results in the generation of heat within the room.

Other sources of generated heat are electrical and electronic appliances as well as the people themselves. If all these factors ‘work’ together in the same room, they can lead to highly uncomfortable levels of heat. As a result, air conditioning becomes a necessity to counteract these conditions.

The article also lists some of the advantages of an air-conditioned environment. According to research, people tends to tire faster in hot temperatures. Additionally, air that is free of dust can circulate inside the room and create a healthy atmosphere. Lastly, outside noise has virtually no way to enter an air-conditioned room because there is no need to open the windows.

All in all, air conditioners and other commercial HVAC systems can provide several benefits that contribute to human efficiency and inhibit the creation of an uncomfortable atmosphere.