Tag Archive for: Energy Audit

Enterprise Holdings now has some specific energy-efficiency options that could improve its bottom line, thanks to a comprehensive energy audit of its facilities performed by MREP.

Enterprise owns seven rental facilities throughout Montana, each comprised of office space and a washing garage, as well as one main office in Helena. MREP experts visited all eight facilities to assist in identifying cost-effective efficiency measures for each building. The recommended measures include installing programmable thermostats for office spaces, insulating gaps in exterior doors, especially under garage doors, and upgrading lighting to LED.


Programmable thermostats are simple to install and inexpensive, yet they can result in significant energy cost savings by reducing the set temperature during times when offices are closed, such as evenings and weekends. Five of Enterprise’s eight offices are recommend to install these thermostats.

  • Annual energy savings: 1,180 therms
  • Annual cost savings: $720
  • Projected cost: $160
  • Simple payback with energy savings: 0.22 years


A number of exterior doors have gaps present, allowing air to flow into the space and negate the heating or cooling from the HVAC systems. Fortunately, there is a simple solution: applying stick-on foam to doors to fill the gaps and help maintain comfort levels in interior spaces. Reducing drafts can also decrease the use of space heaters among office employees, further increasing energy savings.

Garage doors in car-washing areas had large gaps between the doors and concrete floors. The thermal image on the right shows the gap at the bottom of the garage door as it lets cold air in. Adding insulation here will help reduce the need for space heaters and save on natural gas costs.

Weatherstripping is a very inexpensive and cost-effective way to prevent the escape of heating or cooled air. This measure can also be applied to windows and window sills.


Many of Enterprise’s offices and garages had fluorescent T8 tube lighting, and upgrading these to LED will save a significant amount of energy. MREP’s lighting analysis resulted in the following costs and savings:

  • LED replacement cost: $8,332
  • Utility incentives: $3,416
  • Net cost: $4,917
  • Annual energy savings: 43,344 KWH
  • Annual cost savings: $5,285
  • Simple payback with energy savings: 0.93 years


Enterprise Holdings also expressed interest in a solar photovoltaic (PV) system for its Helena and Great Falls facilities. MREP analyzed roof- and ground-mounted systems for the Helena facility and found that a roof-mounted system would be limited to 10.4 kW, which would produce 18% of the building’s electricity usage. A ground-mounted system would allow the maximum size of 50 kW and produce 76% of the building’s electricity usage. The Great Falls facility could accommodate a 10-kW roof-mounted system that would produce about 60% of the facility’s usage.

Currently, there is a 30% tax credit of the cost of the system to any tax paying business. MREP recommended that Enterprise take advantage of this credit while it is still in place as it is set to phase out starting in 2020.

A Montana brewery could save more than $4,000 each year on energy costs by implementing the recommendations of a Montana Resource Efficiency Program (MREP) audit.

Draught Works is a brewery in Missoula, Montana, that resides within a historic brick building built in 1931. The building contains one large room that consists of a taproom and brewery, located on opposite ends of the building. The Montana Resource Efficiency Program (MREP) conducted a detailed audit that focused on energy and water conservation, renewable energy, and operational improvements.

Current heating and cooling equipment includes a geothermal heat pump system (including well pump and circulation pumps). There are also two unit heaters. Ventilation is provided by two heat-recovery ventilators. Domestic hot water is provided by a high-efficiency instantaneous unit to sinks and a dishwasher. There is a 24′ x 24′ cooler inside the building and another refrigeration system for the beer-dispensing lines. The brewery upgraded its lighting LED in 2016.

Audit recommendations include installation of occupancy sensors, ECM motors (brushless, permanent magnet motor integrated with an electronic control module), walk-in cooler evaporator fans, compressed-air system testing and maintenance, and installation of heat recovery-glycol chillers.

The economics associated with the energy-conservation project are summarized below:

  • Total gross project cost: $8,525
  • Total annual cost savings: $4,282.5
  • Total utility incentive: $2,103
  • Net cost: $6,421
  • Annual energy savings: 7,406 KWh and 5,030 therms
  • Simple payback with energy savings: 1.5 years


Darby High School now has great options for energy efficiency in its heating, ventilation, and lighting systems, after an audit by the Montana Resource Efficiency Program.

The high school is a part of a school campus built in 1973 that also includes  elementary and middle schools. There is a small tunnel network below grade that is used for utilities and heating and ventilation system air supply. The building includes administration offices, classrooms, a gymnasium, and locker rooms. The school district replaced the existing natural-gas boilers with a wood boiler in 2003. Figure 1 provides an overview of the temperature and precipitation. Figure 2 illustrates electric consumption at the high school, and Figure 3 illustrates the monthly peak demand.


Figure 1. Darby Historical Weather Data
Figure 2. Electric Usage, 2015- 2017
Figure 3. Electrical Demand,  2015- 2017






Audit Findings:

There are issues with restricted return air that contribute to poor air circulation and temperature control, especially when doors are closed. This high return pressure on the air- handling unit also requires that the air-handling unit fan consume additional unnecessary electricity to operate.

Many of classroom and office heating coils in the branch ductwork in the tunnel have failed, resulting in poor temperature control in those rooms. The heating coils are likely well past their useful life, even though the controls are relatively new.  The school can replace or repair the coils to improve temperature control in the spaces.

The school can save energy in this air-handling unit by converting it to a variable-flow system utilizing a variable-frequency drive (VFD) on the fan and variable-air valves (VAV) on the ductwork to each classroom. This would allow the fan to slow down when less heat is needed and conserve fan power. This measure requires that adequate ventilation air is delivered to each space.

The school could also save energy by converting the heating hot water system to a variable flow system. This upgrade requires valve replacements and additional re-piping on the hot water system. The ventilation for this system comes from a louver in the exterior wall, which likely was originally intended to be open when the mixed air temperature could be maintained well above freezing. This would allow ventilation in all but the coldest periods, thereby protecting the downstream classroom coils from freezing. During the audit, this louver was found closed even though the return air temperature was 65° to 70°F and the outside air temperature was 37°F. Because it was not open, even partially, fresh ventilation air was not being delivered to the academic wing.

School maintenance staff and MREP auditors concluded that previous maintenance overrode the louver system and it no longer opens as designed. The outside air control should be retro-commissioned so that ventilation can be provided at all times, even in the coldest weather. This might require the addition of a preheat system for the outside air system so that the mixed air is sufficiently warmed before being introduced into the building.

In addition to these HVAC efficiency items, the school could save significant energy by converting fluorescent lighting to LED, as shown in Table 1.

Table 1. LED Conversion Project Cost, Savings, and Simple Payback

Project Annual Bill Savings Est. Project Cost Est. Rebate Net Cost KWh Savings Simple Payback
LED Conversion $11,236 $15,804 $10,110 $5,694 87,178 0.5


“Everyone should have an MREP energy audit! I would not have been able to do my REAP grant without them! Danielle was incredibly helpful in finding ways to save money, and getting maximum rebates to help me improve my energy savings. Not only was she insightful and spot-on with her knowledge of energy efficiency and ways to cut costs, she was fun to work with! She would call me up and say ‘I think I found some more money for you, send me your receipts for that!’ I will certainly continue to refer other friends and business owners to her, so they can find ways to save energy and save money!” – Claire Putnam, MD, Women’s Health Services, Bozeman

Dr. Claire Putnam purchased a building on 7th Ave. in Bozeman and planned to remodel the building into a women’s clinic. The one-story building was built in 1940 for residential purposes and converted into commercial space several years later. It currently has an unfinished basement. The remodel was intended to improve the energy efficiency of the building while creating a comfortable space for the patients. The remodel included new windows, a completely updated HVAC system, all new LED lighting, upgraded insulation, and cosmetic upgrades on the exterior and interior.

Total Savings for the Project

This project will save over 14,000 kWh and 107,000 kBTUs per year. That is the equivalent of saving 1,410 gallons of gasoline! The project is outlined in the table below with each elements’ annual savings, cost, and simple payback. The simple payback uses the current utility rates to calculate the cost savings on an annual basis.

Item Conservation Measure  

Annual kBTU



Annual Cost Savings Projected Cost Simple






1. Lighting LED Retrofit 45,788 $586 $1,090 1.09  


2. Window Replacement 54,238 $466 $17,434 39.1 N/A
3. Insulation Upgrade 51,885 $511 $4,716 9.23 $920.00
4. HVAC Equipment Upgrade 35,083 $1,610 $15,176 9.43 $461.30
Totals 186,994 $3,173 $38,416 11.5 $1,813

HVAC Equipment


The new HVAC system includes an ENERGY STAR-rated furnace and air conditioner manufactured by Trane. The old system consisted of an older furnace (assumed rating at 78% efficiency) and a Bryant 10 SEER outdoor unit for cooling. The new furnace is 97.3% efficient with an electronically commutated motor (ECM) for the blower fan motor and a variable-speed drive (VFD) on the condensing unit. The new outdoor unit for cooling has an SEER of 18.

Window Upgrades

The building contained 31 single-paned operable windows. Twenty-one of the windows were equipped with half a storm pane: half screen on the outside, six windows had full storm panes, and four windows had no storm pane at all. Many of the windows were cracked and the storm panes were not installed properly. This project included a full energy-efficient window replacement.

Old upstairs window.

New Upstairs window.

Old basement window.

New basement window

Insulation Upgrades

The project also included increasing the insulation levels throughout the building. The above-grade walls and attic contained an estimated insulation value of R-11. The blown-in cellulose insulation in the attic was not spread evenly and there was no insulation in the roof structure. The basement exterior walls are concrete only with no insulation.

Basement insulation.


Lighting Upgrades
The owner also replaced the halogen track lighting fixtures with new LED flat panel fixtures that are more energy efficient and provide a better quality of light, with a longer service life.


Old track lighting.

LED fixture.


Energy costs for city and county governments are often a very large budget item. But energy-efficiency upgrades can start at a smaller scale and still result in significant energy savings. One such area is street lighting.

The City of Anaconda would like to upgrade its current street lighting to LED to save energy, lower utility bills, and decrease maintenance. Current street lighting varies from metal halides to high-pressure sodium bulbs at four different sizes and wattages.

The Montana Resource Efficiency Program (MREP) conducted an audit of the current street lights by performing a street-by-street bulb characterization and lamp count. MREP then determined that corn-cobb-style LEDs, similar to the LED shown in the image at right, would be the simplest, most cost-effective retrofit for the City.

To allow for resident comment and to ensure that the light is bright enough and the color is acceptable for the area, MREP advised the City to test several city blocks with the recommended LED lights.

If installed, the project will result in the following savings:

  • LED bulb cost: $49,327
  • Utility incentives: $3,846
  • Annual energy savings: $43,336
  • Simple payback with energy savings: 1.05 years


The C Sharps Arms building is located in Big Timber, Montana, and is used to produce custom firearms. The building is divided into two sections, the workshop and the retail/office space. The workshop is the largest section, accounting for approximately 11,100ft2. The building has high ceilings throughout both the workshop and retail spaces, while the offices are standard height with storage above. The basement is used as a packaging area and shooting range to test the company’s products.

Workshop lighting was the main concern for both the management team and the craftsmen. Lighting consisted of (101) 8-foot, two-lamp T12 fluorescent fixtures and (16) 4-foot, two-lamp T12 fixtures. Only 26 of the 8-foot fixtures and nine of the 4-foot fixtures were working or had bulbs. The goal of the management team was to increase lighting in the work areas, while leaving the unused areas dim. There is a second building that had (6) 8-foot fixtures, of which only three were working. The office and retail lighting was also out-of-date, but this was a secondary concern to the workshop. With this type of situation, it was recommended to do a complete replacement of the light fixtures. The table below shows the recommended replacement fixtures.


Current Fixture Number of




Replacement Fixture Replacement




Exterior Wall Packs 5 150 LED Wall Packs 30 120
4ft Fluorescent T12 79 80 T8 18W LED Tube 36 44
8ft Fluorescent T12 39 257 LED High Bay Fixture 119 138
CFL Floods 9 26 18W LED Flood 18 8
Halogen MR16 4 50 7.5 Watt LED 7.5 42.5


Based on these upgrades, this project was eligible for $7,575 through a utility lighting rebate program.  The rebates dropped the net project cost to $4,407. Annual energy cost savings was $2,391, for a simple payback of less than two years.


C Sharps Arms Annual



Est. Project














$2,391 $11,982 $7,575 $4,407 18,373 8.9 1.84 years

Even though the building owners continuously upgrade Bozeman Job Service, Montana Resource Efficiency (MREP) auditors located several cost-effective efficiency measures, all with a payback period of a three years or less.

The Bozeman Job Service is a one-story office building located in downtown Bozeman. In 2010, the building owner installed new furnaces, new ductwork, and fluorescent lighting. The MREP audit identified energy-efficiency opportunities for the plug-load, lighting, building envelope, thermostats, and heating, ventilation, and air condition (HVAC) systems.

Energy-efficiency measures found in the HVAC system include installation of compressors and variable-frequency drives to their existing furnaces. The compressors will have an energy-efficiency rating greater than 12, which will result in savings of approximately 2,600 kWh of energy. The variable-frequency drives (VFDs) will accommodate the demand of air flow through the building. This measure would save approximately 1,055 KWH annually. The economics associated with these two measures is:

  • Annual energy savings: 3,655 kWh
  • Projected cost: $841.63
  • Simple payback with energy savings: 2.57 years

The office also has a large plug-load energy use from computers, copiers, printers, and other large office equipment. This building houses 42 computers with monitors that are powered on all hours of the day due to software and/or computer updates from the state. Each computer uses approximately 1.408 kWh per workday and 1.968 kWh per weekend left running. That adds up to almost 21,500 kWh per year. This is almost half of the building’s current usage. There are two options to cut down on this usage:

  • Computers OFF weeknights and ON weekends
    • Annual energy saved: 7,160 kWh
    • Approximate energy bill savings: $574.66
  • Computers ON weeknights and OFF weekends
    • Annual energy saved: 4,300 kWh
    • Approximate energy bill savings: $354.12

Within the office space, the lighting consists of CFLs and fluorescent T8 bulbs. MREP recommended an LED conversion  with the following economics:

  • LED cost: $5,438
  • Utility incentives: $3,135
  • Net cost: $2,303
  • Annual energy savings: 13,974 kWh
  • Simple payback with energy savings: 1.31 years

Additional energy-efficiency measures identified in the audit include weatherizing windows and doors, as well as programmable thermostat setbacks and scheduling.

A lighting-upgrade project is saving a senior living center in Butte significant lighting energy costs, while providing higher-quality lighting for its residents, staff, and visitors.

The Big Sky Senior Living complex consists of one main building and 12 cottages. The main building contains common areas, apartments, offices, kitchens, dining rooms, maintenance areas, parking garages, a memory care unit, a hairdressing shop, and a physical therapy center.

The Montana Resource Efficiency Program (MREP) performed a detailed energy audit for Big Sky Senior Living, selected the LED lighting, facilitated both the purchase of the lighting and the utility rebate process. Lighting at the complex ranged from metal halide bulbs in parking garage and exterior fixtures, to incandescent, halogen, and fluorescent lights in the interior fixtures. The new LED lighting is more energy-efficient and will provide a better quality of light, with a longer service life.

  • LED Cost:$28,312
  • Recycling Cost: $3,627
  • Utility Incentives: $20,720
  • Net Cost: $11,219
  • Annual Bill Savings: $30,000
  • Annual Energy Savings: 232,000 kWh
  • Simple Payback with Energy Savings: Less than 6 months

Prior to the lighting conversion, Big Sky Senior Living used 731,612 kWh annually at a cost of $73,808, and 13,118 therms of natural gas annually at a cost of $9,038. As a day of service, a group of 15 Energy Corps volunteers and MREP engineers performed the complex-wide light bulb change-out and assisted in packing the 4,300 bulbs for recycling.

Future energy-efficiency potential at the complex includes boiler and hot-water pipe insulation; installing variable frequency drives (VFD) on fan motors of air-handling units, rooftop units, energy-recovery units, make-up air units, condensers, unit heaters, and AC units; installing variable frequency drives (VFD) on the pumps in the hydronic heating systems; installing energy-efficient air-conditioning units; and installing an energy-efficient air-condensing unit for the walk-in cooler and freezer.

 LED Conversion per Fixture Type

Current Fixture Number of Bulbs Current Wattage Replacement Fixture Replacement Wattage Watts Saved
Parking Garage Lights 26 458 150-Watt LED 150 308
Parking Lot, Exterior, and Street Lighting 47 128 64-Watt LED 64 36
Fluorescent Tubes 1914 32 15-Watt LED 15 15
Incandescent 1703 60 9-Watt LED 9 51
Heat Lamps 300 100 9-Watt LED 9 91
Wall Packs 13 70 LED Wall Pack 12 58
Candelabra Bulb 29 28 5-Watt LED Candelabra 5 23
Vanity Bulbs 88 25 2.5-Watt LED 2.5 22
Halogen BR30 75 75 8-Watt LED 8 67
Halogen BR40 75 120 17-Watt LED 17 103


The Best Western Heritage Inn in Great Falls, Montana, is one of the city’s largest hotels. Built in 1972, the hotel is two stories tall with 230 guest rooms, including four two-room suites and five one-room suites. The building also houses a steakhouse, casino, pool, hot tub, bar, fitness center, and 12 large conference rooms in a convention center.

LED Lighting Conversion

Lighting at the Heritage Inn included metal halide bulbs in the parking lot and incandescent, CFL, and fluorescent lights throughout the interior. Based upon the information in the audit, MREP facilitated an LED conversion project. This project had a less than one year payback:

  • Project costs (lights were self-installed): $2,600
  • Utility incentives: $1,482
  • Net costs: $1,118
  • Annual bill savings: $1,995
  • Annual energy savings: 25,935
  • Simple payback with energy savings: 0.56 years

Additional Recommendations in the MREP Audit Report

In addition to the LED conversion, MREP also recommended occupancy sensors for guest rooms and public areas, such as the fitness center, business center, and offices. These sensors could help save as much as 40% more energy by turning lights off in unoccupied spaces. Several occupancy sensor options are available for hotels, including a technology that involves sensors in the key readers. A standard sensor wall switch can cost as little as $10.00 per switch.

Interior Room Heating

The 76 interior rooms and hallways have 10 dedicated electric roof-top ventilators. These ventilators are direct expansion (DX) cooling only, with no heat. Each room is equipped with its own thermostat tied to a duct-mounted electric heater. This allows each guest to adjust the temperature according to their comfort levels. The supply air to these heaters is not preheated and it takes a large amount of energy to heat air when there is a large temperature difference. It would be beneficial to replace the current roof-top units with a gas-fired model. MREP recommended this upgrade only if and when the current roof-top units are replaced or upgraded. The gas-fired roof top units will preheat the air and use a less-expensive fuel. They will also lower the electricity required by the smaller duct-mounted heaters.

Hot Water Heating

Hot water for the entire building, including the pool and hot tub, is heated by three gas water heaters. The main hot water heater for the guest rooms operates at 79% efficiency. By installing a new high-efficiency hot water heater Heritage Inn would save 5,000 therms of energy or $3,500 per year. The cost of a new high-efficiency water heater ranges between $1,500 to $3,000, resulting in a simple payback for this energy conservation measure of three to five years.