How to Cut on HVAC Energy Waste

Lighting and HVAC systems are the primary culprits of high energy bills.   According to the U.S. Department and Energy's Efficiency and Renewable Energy (EERE) arm, lighting and conditioning indoor air makeup more than 50% of a building's total energy use.

For years, lighting has played a large role in cutting energy costs, with very little focus on HVAC. Now advancements in technology are making savings on HVAC systems more achievable.  Likewise, as the saving potential becomes more evident, facility decision makers such as managers and owners are starting to look for opportunities to reduce costs with current HVAC systems.

Three Ways to Cut on HVAC Energy Costs 

1. Fan Efficiency Ratings 

Fans are a large consumer of energy and account for 80% of the so-called parasitic load.   For this reason, the Air Movement Control Association International (AMCA), began developing an efficiency rating for fans.  By choosing a fan based on this rating system, you can reduce a significant amount on energy costs. 

2.Variable Refrigerant Flows 

VRF systems are common in Europe and Asia, but have only recently gained popularity in North America. Its ability to respond to fluctuations in space load conditions, enables energy savings during part-load system use. 

3. Energy Recovery 

Another option for saving on energy costs for facilities is the use of an airside or waterside direct exchange system.  For large facilities, energy recovery systems have the potential to cut energy conditioning energy use by half. 

The Benefits of Displacement Ventilation

One of the most common forms of air distribution for HVAC system is overhead mixing, which is why you will often see air distribution devices--diffusers--blowing tempered air on commercial facilities such as offices, schools and hospitals. 

Diffusers use high pressure to throw the tempered air into a room, mix with the room air and subsequently heat or cool the space.

• Less energy because the space is condition only when occupied

• Less energy from reduced fan power by blowing that air at a slower pace

• Increased comfort of occupants because less air movement 

• Decreased contaminant risks, because there is no mixing of air.  

This technology has its flaws, as the mixed air can be subjected to airborne contamination and consequently lead to poor indoor air quality. Another concern with mixing ventilation is the location of the diffuers. It is common for diffusers to be placed 8-12 ft above the floor. This means that energy is wasted heating and cooling unoccupied space.  

For these reasons, an increasing number of energy and HVAC engineers are turning to alternative designs  in order to temper the space in more effective, efficient and clean ways. 

A popular alternative to this traditional mixing ventilation is a method referred to as displacement ventilation.  Displacement ventilation  is an air distribution technology that introduces cool air to a space at a low velocity through larger diffusers usually located near floor level.  

By utilizing buoyancy forces in a room, generated by heat sources such as people, lighting, computers, electrical equipment, exc., this system is able to remove contaminants and heat from the occupied space.  The conditioned air is then able to migrate naturally to the heat sources of occupants throughout the room. This is due to the fact that heat drives air movement, and since our bodies naturally give off a thermal plume of consistent heat, the conditioned air finds its way to us and cools us off. 

As air conditioned air enters the space, it displaces the room air through natural buoyancy and exhausts through a high point in the room.  Because the the air is not mixed contaminant particles can be removed. 

Displacement Air Ventilation is Recommended

Displacement ventilation is a recommended ventilation system for a variety of facilities because of the above mentioned benefits.  The ASHARE has passed Addendum G to standard 170-2008 "Ventilation of Healthcare Facilities" and recognizes the use of displacement ventilation in healthcare facilities, likewise The Collaborative for High Performance Schools recommends displacement ventilation as the preferred distribution method in education facilities.

Sources: 

Erway, Joel. Engineering.com " Rethinking Air Distribution with HVAC Systems" 15 October 2013. 

Engineering Guide-Displacement Ventilation Guide" 

Sick? Your Air Conditioning Could be the Cause

Is your air conditioning making you and your family sick? 

For many, air conditioning is the embodiment of comfort living, particularly in the summer months when the heat index can be unbearable.  But could your air conditioning be causing more harm than good? 

According to the Director of the Common Cold Centre at Cardiff University in Wales, Professor Rob Eccles, exposing the body to extreme temperatures could actually make you sick. 

 Here's Why: 

As warm blooded animals, the human body's optimal temperature is around 98 degrees Fahrenheit. In extreme cold environments the body will fight to maintain this body temperature.

Cold temperatures cause blood vessels
 to  constrict and diminish number 
of white blood cells.

One of the body's defense mechanisms against the cold is the thermal regulator in the brain. As soon as it receives a message from the temperature sensors in the skin, the blood vessels are alerted to constrict. This immediately causes a person's skin to become ashen or mottle, which is quickly followed by shivering in order to generate heat to raise the body temperature. 

As a result, the blood vessels in the nose and throat, both of which are favorite locations for bacteria and viruses to hide, will constrict therefore limiting blood flow. 

As the blood flow diminishes, the white blood cells that typically fight bacteria and viruses do too. This allows these dormant risks to develop in to colds. Low blood flow to the throat means that there isn't enough white blood cells to ward off infection. 

Sweating exacerbates the problem because it keeps the body colder. This makes it more of a challenge for the body to maintain its optimal temperature. 

Going from hot to cold environments could put
you at risk for a cold. 

Professor Eccles emphasizes that a cold will only develop if the bacteria or virus is already present in the body.  

This phenomenon occurs when going from a hot environment to a cold atmosphere not the other way around. Though, Professor Eccles recommends limiting the number of times you go from a cold environment to the hot outside as when your body acclimates to the heat and steps back inside the chilling cycle will begin again. 

This article was derived from the headline "Does Going from Hot to Cold Cause Colds?" which appeared on August 20, 2013, in the U.S. edition of The Wall Street Journal.