A common inaccuracy that often prevails in the building industry is that energy and energy displacement, and therefore solar energy, revolves solely around electricity.

This perception has become pervasive, and has been fueled by such things as the numerous articles that reference the fact that close to 40 percent of carbon emitted into the atmosphere in the United States originates from the operations of buildings (which is correct) because of the use of fossil fueled powered electricity generation sources (which is not correct).

What is missing here is the heating component. It is a statistical fact that in heating climates, buildings usually use significantly more energy for heating purposes than for electricity (i.e., the 40 percent of CO2 emissions that originate from the building sector represents the sum of two types of energy usage — electricity and heating — not just electricity).

The Hibbing Annex Courthouse is considered to be one of the most energy-efficient buildings in Saint Louis County, Minn. >> Photos courtesy of Conserval Engineering.

Evaluating the Potential for Solar Heating

In the southern states, it is true that a majority of energy consumption occurs because of air conditioning and electricity. But in the mid to northern latitude states, a significant proportion of the CO2 emissions from the building sector arise as a result of heating buildings. Heating ventilation air and general space heating in the spring, winter and fall, as well as water heating throughout the year, usually accounts for upwards of 60 percent or more of a building’s energy usage and corresponding CO2 emissions, and it is this heating component that is so often overlooked.

Now, this statement may seem obvious and rudimentary, but reflect on how often the “renewable generation of electricity” completely dominates the energy discussion, while not giving adequate consideration to the idea of “renewable generation of heat.” The end result can be that businesses and facility managers overlook some of the most cost-effective solar technologies that target one of the largest usages of energy — i.e., the heating component. And, this component of a company’s operating budget is often one of the most under-targeted areas for cost reduction. Given the increasing and volatile nature of natural gas and heating oil prices, the absolute necessity of addressing a building’s “heating component” is starting to gain traction as facility managers crunch numbers and realize that it can be one of the easiest ways to reduce ongoing costs and free up money that can be directed to more profitable uses.

Fifty SolarWall systems of varying colors were installed on 28 military buildings, generating 4MW of peak thermal energy at Fort Drum, N.Y.

Consider the following example. I was recently reading a report in which PricewaterhouseCoopers calculated that in the city of Toronto — which has 4,000 heating degree days, and is therefore comparable to cities like Minneapolis, Detroit or Chicago — 60 percent of the energy used in commercial buildings was for heating, while 40 percent was used for electricity. The proportions were similar for all the other types of buildings examined, as indicated on the graphs on page 32 from the “Background Report on the Energy Plan for Toronto,” done by PriceWaterhouseCooper in June of 2007.

So, given that commercial, industrial, and institutional buildings in heating climates use significantly more energy for heating purposes than electricity, when facility owners are looking to maximize their renewable energy production, it is financially imperative to evaluate the potential for solar heating.

Enlarge this picture SteelCare’s LEED Gold Plant 19 facility, Hamilton, Ontario (CAN), features a 1,500-square-foot black solar air heating system on the south-facing wall. >> Photo courtesy of Conserval Engineering.

Case Study: Steelcare

As shown in the graphs on page 32, the largest single usage of energy in the industrial, commercial and institutional sector is often space heating — specifically ventilation air heating. It is also the area that can yield the most sizable financial savings and offer one of the best energy ROIs on the market. For example, by preheating ventilation air before it enters the building using a solar air heating system, it is possible to displace between 20 to 50 percent of a building’s total heating costs with a payback period that is usually in the three- to seven-year range. Well-designed systems are sized to meet the energy and ventilation requirements of the facility, bringing in anywhere from 2 to 10 cubic feet per minute (cfm) of air per square foot.

To illustrate; Steelcare is an industrial service company, providing sophisticated warehousing, inventory management and transportation to the steel industry. When their Toronto-area Plant 19 was under design, the company began looking at innovative ways to reduce the energy costs of their building while still maintaining the necessary indoor environment. Ventilation air was one of their largest energy expenditures, which is why the company began looking at solutions that would directly impact that energy usage.

A 1,500-square-foot black solar air heating system was installed on the south-facing wall of the 86,000-square-foot building. The system draws in 3,600 cfm of air, and was designed to provide a temperature rise of 77 to 86 degrees Fahrenheit over ambient. (This means that the load on the conventional heaters is significantly reduced — and the daytime load may even be completely eliminated on a sunny day.)

Commenting on their decision to use a solar air heating system to displace the energy associated with heating the ventilation air, Steelcare engineer Bob Edwards said: “Since energy expenses were prohibitive in our other facilities, we had to reduce costs. After we looked at a lot of options, we got a [25 percent grant] to put in a SolarWall [system].” He continues, “With everything we did, our warehouse is 56 percent more efficient than conventional construction, and the SolarWall system represents more than 20 percent of the energy contribution.”

The solar air heating system helped to contribute to five of Steelcare’s Leadership in Energy and Environmental Design (LEED) points, and was one of the reasons the building achieved LEED Gold status. Two points were obtained for EAc1 (Optimize Energy Performance) and three points were obtained for EAc2 (Renewable Energy).

By targeting one of the main sources of energy required in the facility, the system is delivering substantial financial savings.

Commenting on this, Demetrius Tsafaridis, president of Steelcare, relates a humorous anecdote: “Our gas and electric bills are ridiculously low compared to our other facilities. Our gas supplier said we had better get our meter checked because it showed we are using way too little gas!”