Across America, schools are trying to keep aged infrastructure functioning as long as possible in spite of high maintenance and operating costs. Upgrading a building system or replacing a failed major component often prompts administrators to take a fresh look at energy consumption. Energy costs related to major building systems represent a big chunk of the operating budget. System upgrades offer an enormous opportunity for savings.
Schools should maximize the efficiency of the design, maintenance and operation of their core systems: mechanical systems, lighting and controls. The reliability and efficiency of these technologies have improved significantly over the years. To develop a comprehensive, long-term solution — one that can pay for itself over time with energy savings — a school should initiate a feasibility study.
Detailed utility analysis
A feasibility study provides a realistic overview of a school's systems, energy performance, needs and opportunities for savings. An essential component is a utility analysis, which calculates rate structures, costs and usage of electricity, fossil fuel, water and sewer utilities. Schools gather the data from billing information, and utility costs are categorized by both type and BTUs per square foot.
Energy comparison ratios, such as BTUs per square foot, can be important indicators in calculating and verifying potential utility savings. These comparisons can yield a great deal of information. For example, a high load factor with a high kilowatt-hour (Kwh) per square foot may indicate that most of the equipment is operating around the clock; a low load factor with a high Kwh per square foot may show that some equipment is turned off, but too much energy is being consumed when the systems are operating.
A high load factor with a low Kwh per square foot could mean that absorption chillers or other mechanical systems are maintaining steady but low Kwh consumption. A low Kwh per square foot with a low load factor may provide evidence that the building is turning off equipment when it is not needed and is controlling its HVAC systems correctly. This would indicate that engineering time would be better spent on other opportunities.
Two useful comparisons are the effects of weather on energy usage and the load factor, which is the ratio of consumption (Kwh) to demand (kW). Energy usage intensity in BTUs per square foot, when superimposed on a graph of degree days, shows how weather affects energy usage. Observing the spring and fall months, when cooling and heating days overlap, can show if outside air economizing has taken place during those months when “free cooling” is available.
Another use of this information is to determine the base load for gas and electricity usage. The load factor is important in identifying a building's energy-use patterns. Moreover, segregating load into lighting, fan motors, cooling and miscellaneous equipment yields an “end-use profile” that can identify system inefficiencies.
A realistic benchmark
One of the key figures identified through a utility analysis is a school's average energy cost per square foot. This enables administrators to compare energy performance with similar schools in a region and with the state average. This provides a realistic benchmark for potential savings.
An initial facility walkthrough is an opportunity to observe general conditions, lighting, power distribution, energy management/building controls and HVAC/mechanical systems. Operations and maintenance staff provide input on conditions, needs and potential improvements.
The results of a feasibility analysis consist of a utility analysis along with a broad outline of needs for system redesign, replacement or upgrades, projected costs and projected savings. Based on this information, a school may choose to move forward with a preliminary engineering study. This step defines opportunities and projected costs in more detail. It includes a detailed inventory of all systems, components and controls; work sessions to discuss a school's needs and priorities; projected costs; projected payback; financing options; and pre-engineering design.
The information also can be used to create or update formal facility and energy master plans, which enable the school to identify more timely and cost-effective ways to accomplish capital projects.
Martin is manager of corporate development, and Tracy is project development manger with Havel, a mechanical and facility automation contracting company based in Fort Wayne, Ind. Havel is a subsidiary of EMCOR Group Inc., which provides mechanical and electrical construction, energy infrastructure and facilities services. Havel worked on the Christ the King School project (see sidebar).
Energy comparison ratios, such as BTUs per square foot, can be important indicators in calculating and verifying potential utility savings:
A HIGH LOAD FACTOR with a high kilowatt-hour (Kwh) per square foot may indicate that most of the equipment is operating around the clock.
A LOW LOAD FACTOR with a high Kwh per square foot may show that some equipment is turned off, but there is still too much energy being consumed when the systems are operating.
Savings fund an $800,000 energy project
When a 50-year-old steam boiler finally gave out at Christ the King School in South Bend, Ind., the school administration and Catholic diocese initially considered replacing only the boiler, a project estimated at $80,000. But after an in-depth feasibility study, the school and diocese decided instead on an $800,000 system redesign and replacement that will pay for itself in 10 years.
Building walkthroughs and a utility analysis of Christ the King for the year 2003 showed opportunities for significant savings. The steam boiler needed to be replaced, and numerous leaks and other inefficiencies were discovered in the distribution piping system. Based on an average electricity rate of $0.065/Kwh and an average gas rate of $0.75/therm, annual energy cost for the 46,500-square-foot building was $88,225.
The school's average cost of $1.89 per square foot was more than double the 2003 benchmark for Indiana schools — $0.92 per square foot. An analysis of electricity consumption and demand showed that lighting represented more than 32 percent of the school's total consumption (Kwh) and one-quarter of the demand (kW); cooling represented about 35 percent of consumption and half of demand. Moreover, an analysis of annual operating expenses showed total annualized repairs — and thus, potential savings — of more than $42,000 related to chemical treatment, mechanical system, water leakage, lighting replacement and labor, and window air-conditioning-unit replacement costs.
The $800,000 project replaced the steam boiler and distribution system with a new hot-water boiler and distribution system, replaced the window air-conditioning units with a new chiller, added energy-efficient direct-digital controls, and installed new lighting. The new systems yielded sufficient energy and operational savings to pay for the project.