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November 2009

Energy Audits

Use this simple approach to start and expand an energy management program.

Written by Bob Bradbury, Mammoth Mountain Energy Manager | 0 comment

We all have facilities that lose a lot of energy through poor initial construction, hurried remodels, obsolete or outdated heating equipment, poor HVAC controls, and older generation lighting, among other things. But most of steps needed to make these existing buildings less expensive to light and heat are simple and not very expensive.

The first step is to perform an energy audit of your buildings. You can do this yourself, or ask your energy provider to help you, or to recommend others who can. The audit mainly consists of cataloging energy usage in each building and examining the building envelope. Audit your main buildings, lift shacks, pump houses, and any other heated spaces.

A good audit is a hands-on and getting-dirty process. It’s also interactive. Once the audit is done you start to make changes. As you do, keep notes on the work you’ve done. Inevitably, as you go about your improvements, you will notice other items that you should add.


The Outer Envelope
Where to start? The building envelope. Any place there is a penetration of the building envelope, there is a chance for air infiltration. Look at places where beams go through outside walls. Most likely there will be a draft, or you can see light. See if there are drafts coming through door jambs and around doors that are not sealed well. Windows, especially single pane windows, will let a lot of heat out (or cold in). Do your exhaust fans have back draft or powered dampers? This is an excellent place for cold air to push in, or for warm air to exit, when the exhaust fans are off.

Inspect behind lockers, above ceilings, in basements, in attics (some of my best work is done in attics), the outside walls, where walls join roofs. Feel along baseboards for cold air and seal as needed. Good tools for detecting cold air infiltration include your fingers and cheeks. Install insulator pads on electrical and communication wall boxes (switches, receptacles, phone jacks, wall heaters, etc.) on outside walls to stop infiltration.

After you have sealed walls, beams, windows, doors, etc., go back and check on windy days when the wind is from different directions. It is easy to miss some cold air leaks.

Pay attention to your windows. Look for closed drapes that are pushed out by incoming air. Storefront-type windows are notorious for leaking air. Caulking will sometimes pull away from the wall when drying, and may need to be resealed. Big gaps can be filled by backer rod and then caulked.

One frequently-overlooked item in restrooms with exhaust fans is how to draw make-up air into the room easily. If the doors and windows seal too well, the air in the restroom will remain stagnant, and will smell. The solution: install a simple vent register on a lower wall on the opposite side of the room from the exhaust fan. This allows the fan to draw air from another space and vent the smell away. Keeping windows open for ventilation just lets the heat out.

In locations such as restrooms, air-to-air heat exchangers can use the warm exhaust air to preheat the cold incoming makeup air without mixing the two. Typically, you can reduce your heating costs in these areas by at least two-thirds.

Doors also deserve special attention. Slow the air going though the building down, and you will reduce your heating costs. Do you have any double doors that face the wind and blow open all the time? These doors let a lot of cold air in at a time you are at maximum heating load. Do you have entry areas that get a lot of ice and snow buildup on the floor and keep the doors open? Solve those issues!


Taming the Lift Shack
Lift shacks are notorious energy guzzlers. We all have quite a few and they tend to be neglected. But they are typically heated 24/7 and are a large collective expense. Installing programmable thermostats or twist-type timers on the heaters can create huge savings. On older lift shacks, installing a twist-type timer will keep the heaters from running all night, and keep the heat off on days when the lift is not operating. Installing programmable thermostats on newer lift shacks with electronics in them (if you can keep employees from fooling with them) also pays for itself quickly. Sealing shacks better and installing thermal pane windows will make a difference in both energy usage and employee comfort.

To cut heating costs at Mammoth, we have installed heater delays in the shacks to turn off the heater if the door is left open for more than five minutes, and will turn back on when the door is closed. Employees tend to regulate the lift shack temperature the same way they do in employee housing—by opening the door or windows. With a delay, if they get cold, they close the door and the heat will come on. Retrofitting controls on electric and gas heaters can be quite easy; as always, though, only qualified people should work on these systems.

Older fixed-grip chairlift terminals typically do not need heat to keep sensors warm. The heat here is mainly for the lift mechanic’s comfort. On the newer detachable lifts there is a need to keep some sensors warm. Usually, leaving the heat on is a poor way to accomplish that. Heat rises, and these sensors are located below the floor plates. It’s more effective to heat that area with a small 500 watt (or smaller) electric heater rather than one or more 10 kw electric heaters. A timer and/or thermostat can also be installed. (This also applies to tensioning systems.) For the terminal heaters, install the appropriate voltage mechanical timer. The internal thermostat can be set to around 45° F, so it only runs when the temperature is lower. During the off season, leave the off timer in, so if someone turns on the heater at the timer, it will stay on no more than one day, instead of weeks or months.

Installing programmable thermostats in other heated spaces can result in a huge energy savings. People tend to leave heaters on overnight, so that their space is warm in the morning when they come to work. With programmable thermostats, the heater is turned down at night and back up in the morning. Electric wall heaters can also be controlled with programmable thermostats. The only problems with these thermostats are 1) some people fool with the program and 2) changing the clocks for daylight savings time can be a bit of a task.


Tracking Energy Use
To learn what the energy usage is in each building, install heating fuel and electrical meters on each building. Any building over 10,000 square feet should have a meter. Simple electrical sub meters can be installed for under a thousand dollars. More expensive sub meters will allow you to remotely read and graph time of day usage, which is extremely useful— night usage will surprise a lot of people. Time-of-day meters show what appliances are being left on (perhaps unnecessarily). Heating fuel meters can help to pinpoint inefficient heaters and controls as well as building envelopes; make sure they are in a place where you can easily read them in winter. I convert heating fuels and electricity into millions of BTUs to compare energy consumption in mixed-use buildings. Look at the energy usage per square foot and compare your buildings to one another and to the national average for your climate zone.

I track energy usage in each building by cost and by BTUs each month, which eventually provides a multi-year history to track successes and failures.

But you don’t have to track energy use that closely to see a difference. The important thing is to get started, and the sooner the better.

Funding Further Savings
Use the money saved through efficiency to fund more complex projects. Many utilities offer grant programs to help you reduce energy usage. Depending on the type of grant, the paperwork can be easy. Most grant projects will pay for themselves in less than a year, and the grant money is the gravy that can help you fund more projects. Also, make a deal with your finance people to use grant money to fund more projects that would otherwise be considered capital expenses, and/or to use some of the operations money saved through energy reductions to fund more money-saving steps.