Energy is expensive and buildings use a lot of it. Buildings account for 77 percent of electrical use and 43.5 percent of all energy use in the United States. Over the life of a building—whether 25 or 100 years—the cost can add up to either dollars down the drain or a significant source of savings, depending on the level of energy efficiency built into the structure. Experience has shown that you can achieve energy savings of 50 percent or more. This article outlines four practical steps you can take in planning for an energy-efficient and cost-effective fire station. It also provides you with a framework to decide which energy savings measures will best fit your budget and needs.
Heat loss and heat gain
The first step is to reduce heat loss from the interior of the building, or to have unwanted heat gain from the exterior. Having proper insulation levels is the single most important step in having an energy-efficient building. Because of this, building codes specify insulation values for walls, windows, doors, etc. Current codes should be considered the minimum levels to be achieved, not your goal. This is because they reflect current energy economics and ignore completely the fact that your building occupants will be buying energy at rising prices for many decades to come. We build in the Northeast and the insulation levels that we strive for are R-32 for walls and R-38 for the roof, which is roughly 50 percent above code. We limit the R-value for the roof to 38 rather than 50, or greater, because, unlike the walls, it will be relatively easy to increase roof insulation in the future. These values are appropriate in northern climates. You will need to work with a local energy engineer to determine the best R values for your climate.
Whether you're trying to minimize heat loss in the North or heat gain in the South, you need to go through similar steps to correctly determine the best insulating levels for the building envelope. Every element of the building needs to be considered for its insulating characteristics and its air tightness. This is often overlooked when it comes to the overhead doors, which can represent a significant percentage of the apparatus bay walls and are the largest source of uncontrolled air leakage in the building. The R-values of these doors can range from below 5 to above 16. Select building systems that minimize or eliminate what is referred to as thermal bridging, building elements that conduct heat through the insulation such as steel studs and the webs of concrete blocks. These can result in wall R-values that are less than half of the stated R-value of the insulation. It is essential if you are using either of these materials to have continuous rigid insulation on the cold side of the wall assembly. If you are planning to use a metal building system, carefully study the wall insulation details to make sure that the insulation does not become compressed to the point where the R-value is significantly reduced.
An airtight building envelope is required for an energy efficient structure. The building and occupants should get the required fresh air by using a well-regulated ventilation system, not through leaky walls, windows, doors, ductwork, louvers and roof that can lead to condensation in the building envelope and mold growth. Heat recovery ventilation can provide for the health and welfare of the occupants while recapturing more than 50 percent of the energy in the exhausted air.
Energy-efficient equipment
The second step is the inclusion of energy-efficient equipment into your station's design. Currently available heating equipment efficiency can be as low as 80 percent or greater than 96 percent. HVAC system pumps and fans need to be sized for the maximum load. As a result, they can be using more energy than necessary 95-99 percent of the time, representing 28 percent of total electrical usage and 15 percent of the demand charges. With a variable frequency drive, a 50 percent reduction in speed can result in a 90 percent reduction in energy use.
Lighting typically represents more than 25 percent of your electrical usage. In addition to controlling the amount of time the lights are on through timers, daylight sensors and occupancy sensors, you should pay attention to the efficiency of the fixture itself. This is measured in lumens of light per watt of electricity used (lpw). Here are some examples with expected luminaire lifespans:
- Incandescent—14 lpw, with 1,000 hour expected life
- Compact fluorescent—61lpw, with 8,500 hour expected life
- Metal halide—66 lpw, with 5,600 to 20,000 hour expected life
- LED—up to 300 lpw, with up to 50,000 hour expected life
Smart control systems
The third step includes the use of smart (but not too smart) control systems. Here are two simple mechanical system control strategies you can use:
- Use occupancy sensors to control room temperature as well as turning on lights.
- Use carbon dioxide monitoring of the air to set ventilation rates to reduce outside air volumes when the building population is low, while maintaining a healthy environment.
Alternative energy sources
The fourth step is to consider any alternative energy sources. After all of the other steps you should consider:
- Daylighting—The U. S. Department of Energy estimates that you can achieve cuts of as much as 80 percent in artificial lighting use during daylight hours, and apparatus bays are ideal for the installation of high-efficiency skylights.
- Passive solar—A south facing window is a passive solar collector, a heating method that has been used for thousands of years. Design your site and building to make use of this.
- Active solar—The city of Madison, WI, reports the solar hot water systems they have installed in their stations have a three- to five-year payback.
- Ground source heat pumps—A ground source heat pump works the way your air conditioner (or heat pump) works to move heat from one place to another, but instead of using the air as a source of free heat or cooling, it uses the ground. The efficiency of a ground source heat pump can be two to three times greater than an air source heat pump. The Madison Fire Department reports paybacks of five to eight years.
How to decide?
First, use a cost versus life cycle cost analysis. Because every budget has its limits, you need to decide early in the design process which energy saving measures to select. There’s a large range between simply following code and building a “net-zero” energy facility (utility cost of $0 because the building produces as much energy as it uses each year). Two ways to decide what to do are “shortest payback” and lowest “life-cycle-cost” (LCC).
Shortest payback means listing measures that will pay themselves off in the least time, and selecting items from the list until your budget is spent. An LCC analysis looks at each measure with both the first cost and with total cost of ownership over time, including maintenance, longevity, replacement cost, and the harder to quantify costs of system failure.
The shortest payback approach is by definition short-sighted. In contrast, the item with the lowest LCC may not pay itself back as quickly, but will be a much better investment in the long run. The LCC approach can evaluate all aspects of the building, including those harder to measure factors such as the health of the building’s occupants and the physical environment’s impact on worker productivity.
Wanting an energy-efficient building and successfully constructing an energy-efficient building are two different things. You need as much information as you can get early in the design process so that energy-related decisions are based on facts. Energy modeling is a computer simulation that describes how building materials, construction details, and systems and equipment choices will contribute to energy savings. Working with an estimator, the energy model allow you to decide either the payback or LCC.
During construction a commissioning agent examines the work to make sure that the building envelope and mechanical systems are built as designed to achieve the energy savings that were intended. The commissioning agent should be brought in during the design process to review the plans based on their experience in the field.
In Closing
Following these energy-saving steps will make a real difference over the life of your building and will provide long-term payback. To make energy savings a reality, and not just a good idea that gets left behind as you plan, it will be important for department decision-makers and personnel to understand how planning for energy efficiency can save energy and dollars over the long term. In addition, you can assist local officials and the community you serve to understand the importance of investing in energy efficiency. You want everyone to know that the bottom line is not just the cost of the building now, but the cost over time. As a hallmark of thoughtful, dollar-smart, and responsible planning, you can build your new station keeping in mind that your children and grandchildren will be paying future operating costs. Following these steps you’ll know that you have made sound decisions that allow future generations to look back and thank you for the careful stewardship you gave to the project.
BOB MITCHELL is the principal of Mitchell Associates Architects in Voorheesville, NY, a firm whose entire focus is public safety architecture. He has over 20 years of experience designing fire stations, and has been directly involved in over 150 fire stations and emergency services facilities. Mitchell has completed more than 50 feasibility studies evaluating renovations and additions to existing emergency services facilities versus building new. In the 1970’s and 80’s Mitchell's work converting old buildings into passive solar, energy efficient structures received national recognition.
