Silent Killers of Energy Performance

By Andrew Boyd, The NEBB Professional — Q2 2021 Edition

Medical professionals describe high blood pressure as the “Silent Killer”. With no obvious symptoms, negative consequences occur if not treated. Similarly, I believe that there are numerous “Silent Killers” of energy performance in buildings; conditions where occupants are not whining but utility bills are higher than they should be. Here are a few of my favorites: (with apologies to The Rascals)

It’s 60 degrees and 50% relative humidity when you, as the building manager or controls technician show up early to work. After your Starbucks, you should check to make sure the outside air dampers are wide open, as are the relief dampers, and the mixing damper is closed. Hot and Cold coils should still be sleeping in their “off” position. If not, there could be something amiss with the economizer cycle. This is a perfect opportunity for the building HVAC system to take advantage of free cooling, flush the building with lots of fresh air, and reduce fossil fuel use. Time for some sleuthing if the settings are not as described. (with apologies to David Bowie)

The consensus among mechanical engineers is that a building should be under slight positive pressure to prevent infiltration. A few wise apostates may argue in climate zones 5 and above during the heating season it should be negative to reduce moist air condensing in the walls – but I digress – and a trip to Key West during February with libations may cure them of this delusion. Awareness of building pressure, both direction and force, will help discover potential problems.

I like to carry an inexpensive manometer during building surveys, or being my forgetful self, grab a strip toilet paper from the restroom as a sophisticated visual indicator. Check differential pressure at ground floor entrance doors and vestibules, noting readings that suggest poorly sealed vestibules. A quick check at stair towers can give an indication of stack effect; if egregious go up and remove the wedge at the roof penthouse door that maintenance folks used when they forgot the key.

Look for excessive pressure in the building and confirm if so, that the static duct pressure is excessive at the controls front end. If VFDs are running wide open, investigate. If the building pressure is neutral with the VFDs in this condition, it could be a sign of a very leaky building enclosure. Poor building pressure control could also indicate poor coordination of the sequence of operation with supply, return, and relief fans.

You have probably had the experience of trying to open the door of your local pizza joint and finding it an unexpected test of your manhood as you struggle to enter. Obviously, the hoods are not balanced, and conditioned air is vainly trying to provide make-up air. Buy a pitcher, invite the manager over, and suggest he or she consider upgrading to a more efficient hood system that balances exhaust with outside air, and uses a VFD to vary the fan speed depending on load. The energy savings – not to mention January customer comfort – may result in free pitchers for life. (with apologies to Sting)

Ever been in the mechanical room with its low murmur of running machinery when you are suddenly startled by the staccato rhapsody of the air compressor kicking on for the pneumatic lines? Typically, I am crouched under a large strainer valve when my head jerks up. Make a mental note of the run time of this device, since longer run times suggest air leaks in the system.

Electric motors use around half of all electric energy in the US, and starting amps create a stressful load on the electrical system each time the motor starts. One building we surveyed had a compressor that never ceased running, not only adding its KW load but also the latent energy load for the constantly dripping condensate. (with apologies to The Chicks)

Our team was called to a LEED certified building with excessive propane use in primarily the swing seasons. The facility had a high-bay maintenance area for vehicles, with large garage doors, conveniently facing South. On a beautiful sunny spring or fall day with temperature in the high 50’s the crews put on their light fleece sweaters and worked with the doors open to enjoy the wonderfully comfortable conditions.

The poor space thermostat, however, did not find the conditions so salubrious and insisted on trying to heat the entire county. A simple cut-off switch to disable the heating system when the door was open solved the problem. The design of the building was fine, and the system was highly efficient – but the designers did not fully realize the irrationality of the human occupants. (with apologies to Jimmy Cliff)

I once sat in a cubicle with an attractive window which was perfect for daydreaming and forgetting meetings. During the winter months, from approximately 9:00 to 11:30 AM there was excessive glare on my monitor, and I had to pull the shades down. After lunch I raised them. With the adequate natural light, I turned off the overhead lights and saved energy.

The occupant of the adjacent cubicle enjoyed the natural light spring through fall, and then closed the shades when the dreaded winter glare arrived. The shades stayed down for the next year, and he turned on the overhead lights to compensate, usually forgetting to turn them off when leaving for the day. It is hard to change human behavior without the lash and withholding grog but building managers and occupants should be encouraged to use window shades to control temporary glare only as needed and enjoy natural light and views both for mental health and energy savings.

I have also found several instances at double-hung windows of insidious energy pirates. As an architect, these wonderful 17th century inventions are a great part of the design tool kit. Hard to imagine Monticello without them. Before air conditioning, lowering the upper sash could provide much needed ventilation while keeping the lower portion of the opening sealed from rain.

Traditionally they were controlled with weighted sash cords; current windows typically use springs to control position. Too often the springs weaken or the cords release, and the upper sash sags permanently from the closed position. Those attractive window treatments often hide the sin. When surveying a building with double-hung windows, make sure to reach above the upper sash, especially on cold days. You may want to bring your gloves. (with apologies to the Shakers and Aaron Copeland)

Lowering your blood pressure is elementary simple. Just reduce your weight, exercise more, stop smoking, drink less alcohol, and reduce stress. Simple – even in a pandemic. Easy for all of us – right. Examples of energy silent killers like those above are insidious in part because they are so easy to correct and because they are top-right quadrant of the Eisenhower Decision Matrix.

A roof leak at the CEO’s office, top-left quadrant, gets fixed right away (Important and urgent). A poorly controlled VAV with simultaneous chilled water and reheat may be locked in a duel of energy profligacy resulting in a draw but have comfortable space temperatures. Top-right quadrant (important but not urgent) – and may never get addressed.