Technical help

Case example

September 1998

Q: What energy management projects can we recommend for fast food restaurants such as McDonalds, Burger King, etc.?

A: Thank you for contacting The Power Line. Restaurants are very energy intensive operations with Energy Use Indexes ranging from 350,000 to 400,000 Btu's/Sq. Ft/Yr.  Costs are often several dollars per square foot per year.

McDonalds, Subway, Arby's and Burger King are just a few of the chains that have undertaken projects. Here is a list of energy measures for improvement in restaurants that were compiled from an assortment of articles. Please do not consider this list fully complete, rather it includes some more common measures.

• Photo-sensor controlled dimmers
• Skylights that redirect the sun's rays through reflective tubes
• Occupancy sensors in walk-in coolers and freezer
• Lighting upgrades--efficient lamps, electronic ballasts
• Efficiency metal halide on interior, when applicable, and in parking lots
• Triple-paned "heat mirror" windows with features to reduce exterior heat-gain
• Air-to-air heat recovery
• Heat pump water heater
• High-efficiency exhaust fans on fryer hoods, griddle hoods and bathroom ventilation
• Building automation system to control lighting, heating, refrigeration and air-conditioning (can also be incorporated with safety and intrusion monitoring controls)
• Geothermal heating/cooling
• Cooling with heat pumps
• Variable speed heat pumps
• Solar/electric desiccant air-conditioning
• Reduce/improve exhaust flow rates
• Exterior photovoltaic lighting
• Fuel switching--electric-gas-solar
• Bill auditing and verification, utility payment processing, tariff review services and energy usage analysis.
• Catalytic process to clean grill exhaust
• Refrigeration waste heat

Attached for your reading are the following items:

• Nation's Restaurant News: "It's More than Just Lights," New York; Nov 3, 1997.
• Air Conditioning, Heating & Refrigeration News, "McDonald's goes underground: Fast-food chain tries geothermal," December 15, 1997.
• Florida Energy Extension Service factsheet. Energy Efficiency & Environmental News: Hospitality Industry, June 1994.
• Berkley Applied Science and Engineering Inc. Web site
• CADDET Energy Efficiency website article. Energy-efficiency fast food in Australia

I hope this information satisfies your needs. Feel free to call The Power Line at 1-800-769-3756 if we can assist you further. Please fill out and return the enclosed evaluation card so we may continue to improve our services.

Sincerely,
Scott Wolf, Energy Engineer

Q: What are the horsepower requirements for a 200 sow hog confinement operation (single building)?" Some considerations are ventilation and waste; they are unsure if they will use a lagoon or pit for waste. This will be a year round operation in SW Minnesota. The sows will be in the building from farrow to market weight.

A: Thank you for calling The Power Line for information about power loads of a sow hog confinement operation. Ventilation systems will vary depending on whether or not a waste pit is installed into the facility, as well as other important design variables. If the waste pit is installed, it will definitely increase your ventilation fan motor horsepower requirements.

Past documentation reveals that separate ventilation rates are recommended for each hog unit in the confinement. See the following enclosures:

• "Fan Performance and Efficiency...," University of Minnesota, pg.2
• "Ventilation Fans: Efficiency and Maintenance," University of Nebraska, pg. 3,4, table 1 & 2
• "Ventilation Systems," ASHRAE, pg. 5,6
• "Manure Pit Ventilation in Confinement Livestock Buildings," Purdue Univ., pg. 2

To assure efficiency and the load the fans will encompass, account for the static pressure of the building, the manure handling (pit or lagoon), the fan types and sizes, natural ventilation systems, and other pertinent design factors of the facility. This can be calculated by the design or agricultural engineer.

To get estimated power requirements or the size of the load for the entire confinement, your will need more specifics on the design of the building. Lighting, miscellaneous power requirements, HVAC, plumbing/sanitary equipment and other special equipment will need to be factored in to get an estimated size of the entire load.

As an example of what it will cost in utilities alone, Oklahoma State University Extension Service estimated $36/sow. (See enclosure "Economics of a 140 Sow, Farrow to Finish Confinement unit," Oklahoma State University Extension Service, pg. 3,4, table 5) Another example, yet possibly outdated, was estimated by a study in 1989 that total annual fuel and electricity averaged about 1200 kWh/sow farrow-to-finish. (See enclosure "Energy Use in the Production and Housing of Poultry and Swine--An Overview," Canadian Journal of Animal Science, pg. 9,10) There is also a sample financial analysis spreadsheet available for downloading from the University of Minnesota Extension Service. This will estimate the utility/energy cost of the swine confinement, as well as the entire confinement costs and profits. The URL is (See enclosure "Pignet: A Tool for Financial Analysis of Swine Production Networks," University of Minnesota Extension Service, pg. 1,2)

Another resource is the MidWest Plan Service (515/294-4337 or website http://mwps.onplanet.com/ ). They can help with estimating the load size of this facility. They also have a publication, "Swine Housing and Equipment Handbook," MWPS-8 ($8).

Another option that may help is contacting a peer utility that regularly deals with swine confinement operations. They may have energy use profiles established from existing accounts and may have a comparable operation to reference.

With the information that we have, an estimate of the load size and horsepower requirements is unattainable. If you would like to discuss this further or have any additional questions please call The Power Line again toll-free at (800) 769-3756. Enclosed is information we have gathered which will help with design requirements and planning. Thank you for using The Power Line.

Sincerely,
David Shepherd-Gaw, Technical Assistant

Enclosures:

• "Fan Performance and Efficiency for Animal Ventilation Systems," University of Minnesota
• "Ventilation Fans: Efficiency and Maintenance," University of Nebraska
• "Ventilation Systems," ASHRAE
• "Manure Pit Ventilation in Confinement Livestock Buildings," Purdue University
• "Recommended Ventilation Rates"
• "Ventilation Design Data"
• "Economics of a 140 Sow, Farrow to Finish Confinement Unit," Oklahoma State University Extension Service
• "Energy Use in the Production and Housing of Poultry and Swine--An Overview," Canadian Journal of Animal Science
• "Pignet: A Tool for Financial Analysis of Swine Production Networks," University of Minnesota Extension Service
• "Planning Information"
• "Space Requirements for Swine," Pork Industry Handbook

Q: Is electric baseboard heating a good choice for a cabin I'm building at about 9000 ft altitude? I expect it will get little use because of solar gain in the house. The cabin will be approximately 1100 square feet, roof insulation R48, log cabin with walls 8 inches thick, basement and subfloor fully insulated with 8-10 inches fiberglass insulation, double-glazed low E high-altitude windows (installing two french doors, the rest will be normal sized aluminum clad, wood frame windows).

A: Thank you for calling The Power Line. You have asked for information on electric baseboard heating. I have addressed this issue, as well as enclosed information on other types of electric resistance space heaters and controls. The text below has been supplemented by several articles on the subject and a list of suppliers you may contact for specific equipment information. I have also added a report on log home construction and a short article on passive solar heating that may apply to your project.

Electric Resistance Space Heating
All electric resistance heating equipment converts electrical energy to heat at the same efficiency. Electric resistance heating equipment produces 3413 British thermal units of heat for every kilowatt-hour of electrical output. Annual heating bills can be reduced by selecting electric resistance heating equipment and controls that deliver the heat where and when the occupants need it, rather than heating the entire home or heating around the clock regardless of occupancy.

The primary advantage of electric resistance space heaters is the ability to individually control each heater. Homeowners with this type of heating equipment are much more likely to use lower thermostat setpoints in unoccupied rooms of the home. This leads to lower overall heating energy use. I have enclosed a Technical Brief that describes this concept further as well as the various types of heating equipment which could be used to achieve it.

There are a variety of electric resistance heaters available on the market. Each has advantages and disadvantages. Below is a description of the most popular systems and common installation practices. The challenge is to select a system that best matches your lifestyle.

Electric Baseboard Heaters
Electric baseboard heaters rely on natural convection to circulate air past the electric heating elements. Electric baseboards are frequently used under windows. This placement counteracts cold drafts falling off of the window surface. Even though you have selected high quality windows, this placement technique is still sound. However, it is best to avoid a window treatment such as curtains that will funnel that hottest air into the space between the window and the curtains and thereby increase heat losses. Electric baseboards are typically 8-10 inches tall and 2-8 feet in length. Heating capacity is approximately 250 watts per liner foot. Baseboard heaters are inexpensive and quiet. The large amount of wall space they use can limit placement options for furnishings and drapes. Some models are available which use fluid-filled piping as thermal mass to flatten out the space's temperature swings.

Fan Assisted Electric Heaters
This type of heater uses a small quiet fan to distribute heat from the heating elements into the room. Because the fan blows the heat out of the unit, a higher heating capacity can be enclosed in a relatively small unit. Heating capacity ranges from 500 - 5000 watts. The relatively small size makes it easier to install the needed heating capacity with limited impact on furniture placement. There are a number of types of fan assisted heaters. Wall mount is most common. Ceiling and in-floor heaters are also available. Where cabinets are to be installed, kickspace heaters are available. Because these units utilize a fan, some people do not like the noise or drafts they create.

Electric Radiant Panels
Electric radiant panels enclose electric resistance heating cables in a flat steel panel. This configuration reflects most of the heat away from the heating panel. Radiant heat is transferred from the panel to people or objects rather than heating the air, although eventually the heated objects will heat the air as well. Radiant panels are most frequently installed on the ceiling. They are also installed on walls. Some wall-mounted units are painted to look like artwork and can be quite attractive. A 2 x 2 foot panel will typically provide 375 Watts of heat. Because these units are lightweight, they can provide heat almost instantly. Because radiant panels work best when they directly heat the occupants, it is important to place the heaters where the occupants will spend most of their time.

Electric radiant heating equipment has recently received some positive evaluations.   Enclosed is an article describing a study conducted by the National Association of Home Builders. This study suggests that electric radiant panels can reduce heating energy needs by 53 percent when compared to electric baseboards. It should be noted that this is a limited case study. Rather than concentrating on the savings numbers, I suggest you read this article to determine if this type of heat will fit your lifestyle. Are there places in your home where this type of heat would make you more comfortable? Refer to the enclosed article, "Research Supports Benefits of Radiant Ceiling Panels," for additional information.

Electric Heating Cables and Mats
Electric heating cables allow the builder to incorporate heating elements in concrete, masonry and tile building components. Long rolls of cable are used to heat lightweight concrete floors that are 1/2 to 1-1/2 inches thick. Cable is installed in a pattern that delivers the appropriate heating capacity to a given square footage of the building component. Carpet or wood flooring can be laid over the top of the concrete underlayment, but a ceramic tile floor will provide the best heat transfer. Because the concrete is heavy, this system may take several hours to heat up after thermostat setback.

Electric heating mats are pre-constructed webs of cable incorporated in a fiber blanket. Mats are thinner than cables and can be placed behind tile floors or walls without additional concrete. Because the heating elements in mats are smaller in diameter, the heating capacity per square foot is lower.

Electric heating cables and mats provide a radiant source of heat. To maximize the benefits of radiant heat, thoughtful placement of the elements is required. Kitchen eating nooks and bathrooms are popular spots for radiant cables. Put these heating elements where people will be treading around in their bare feet. Refer to the article, "Electric Radiant Heat: Making the Right Choice," for additional information.

Controls
Most electric resistance space heaters are controlled using bi-metal thermostats. New electronic line-voltage thermostats are being introduced that provide additional features and more precise control.

Bi-metal thermostats are inexpensive and reliable. They are not precise instruments. Heating setpoint is usually limited to "off," "warm," and "hot." The temperature differential at any given set point may be as much as 6-8 degrees. More expensive bi-metal thermostats will have differentials of only 2-3 degrees.

Electronic thermostats provide more precise response. The user can select exact temperature setpoints. The temperature differential at any given setting is usually limited to 1 or 2 degrees. Units with temperature settings as low as 40 degrees are available. This may be useful for providing freeze protection when your cabin is unoccupied. Electronic line voltage thermostats are available with time set features for automatic control. Electronic line voltage thermostats cost run from $30 to $85. Refer to the article, "Do New Baseboard Thermostats Save Energy?" for additional information.

Improving the Energy Efficiency of Log Homes
The level of insulation and low-E windows you have selected for your log home indicate you are planning to construct a high quality building. One item that is frequently overlooked in all types of construction is high quality air sealing. Paying particular attention to air sealing details in your log home will improve the comfort and energy efficiency of your cabin. I have included a copy of "The Thermal Performance and Air Leakage Characteristics of Six Log Homes in Idaho." There is an excellent section in this paper describing air leakage control techniques. I suggest you review pages 16-24 for tips on air sealing log homes.

I have also included a brief article on solar heating. "Turn to Solar for Lower Heating Cost" provides a simple set of rules for maximizing solar heating benefits. If you would like more information on this subject, we can provide more detailed methods for maximizing solar heating in your home.

If you have any additional questions, please call The Power Line again at (800) 769-3756.

Sincerely,
Chuck Murray, Energy Specialist.

Enclosures:

• "Zonal Electric Heating", a Technical Brief from EPRI
• "Do New Baseboard Thermostats Save Energy?" from Home Energy magazine
• Product literature from Cadet Manufacturing Company
• "Research Supports Benefits of Radiant Ceiling Panels" from Iris Communications
• "Turn to Solar for Lower Heating Costs" from Northwest Builder
• "The Thermal Performance and Air Leakage Characteristics of Six Log Homes in Idaho" from BPA's RCDP Cycle 3

Q: How can we update our computer center to comply with codes and to have uninterruptable power sources (UPS). Should we use a voltage recorder to monitor voltage spikes and see if we have any problems?

A: Thank you for calling The Power Line. I discussed your situation regarding transient monitoring and UPS plans with our own computer systems analysts. We have a 10 kVA system with several hours of backup time. Backup is provided by battery power. The system operates continuously, providing power conditioning even when there is no interruption. Essentially it consists of a rectifier/battery charger and a sine wave inverter powered by the batteries. It sounds like a similar system may well serve your needs although your capacity may be considerably different.

There are a number of systems available that allow ride-through of faults lasting several seconds. Some of these use "super capacitors" or inertial storage type devices. However, your situation, which requires perhaps 15 minutes to protect data and accomplish an orderly computer shutdown, probably requires a battery-based system similar to our own. We recommended that sizing be based upon an actual survey of maximum combined power draw rather than a summation of nameplate watts or a total circuit capacity. Depending upon your expectations of growth and level of uncertainly, a safety factor of about 50% oversizing relative to the survey is advisable. Basically, you will have to define your required capacity in kVA and the minimum time you have to remain powered at that kVA.

Running the system continuously as a power conditioner will reduce any concerns of switching transients or transfer faults when a power failure occurs. It will also inherently protect against spikes which is one of your concerns.

You probably will not be covering all your computer loads with the UPS. There are some things you can do to protect the entire system from power quality problems that might affect other computers. These are mainly applicable when expanding your computer systems. They include mixing wye and delta secondaries throughout the facility to phase shift some of the loads so they don't all gulp current at the same moment. Another is to oversize neutrals to reduce neutral-to-ground voltage and implement a robust grounding system including dedicated grounds and even dedicated neutrals.

You asked about a logging system to detect and record spikes. A number of power quality recording systems and "traps" are available. We do not have the means to evaluate and report on their comparative value, but we always are happy to relay information when manufacturers provide us their literature. In that regard, Dranetz has recently provided us with material on their power quality recorders. They have systems that can be programmed to detect an anomaly like a voltage spike or capacitor-switching transient, and capture and retain wave shapes over several cycles for later analysis of the events. Further information on their products can be obtained at 1-800-372-6382.

Fluke Corporation also has an interesting product that they advertise as ideal for capturing spikes up to 2,500 volts, etc. They claim their VR101S is the perfect system for catching sags, swells, transients, outages and frequency variations on line voltage at receptacles, where the most sensitive loads are connected.

I hope this has been helpful. If we can be of further service, please call The Power Line at 1-800-769-3756. Also, we would appreciate it if you would fill out and return the enclosed evaluation card so we may continue to improve our services.

Sincerely,
Johnny Douglass, P.E., Senior Industrial Engineer