What Does a Net-Zero Energy Building Really Mean?

The following article is taken from a newsletter published by Estes McClure and Assoc Inc., Nov 2012.


In the ongoing quest to decrease the impact buildings have on the environment, we have begun to hear more about the concept of net-zero-energy buildings. The term itself sounds impressive. After all, when looking at low-energy use, how can you beat zero?

But exactly how do you define a "net-zero-energy building"? A clean measurable definition is needed because the way the "zero-energy" goal is defined affects the decisions Architects, Engineers and Owners make to achieve and measure success. Let's look at some of the definitions in the market place today.

Net-Zero-Site Energy: A site Net-Zero-Energy Building (ZEB) produces at least as much energy as it uses in a year when accounted for at the site.

Net-Zero-Source Energy: A source ZEB produces as much energy as it uses in a year when accounted for at the source. Source energy refers to primary energy used to generate and deliver energy to the site (from a power plant, etc).

Net-Zero-Energy Cost: In a cost ZEB, the amount of money the utility pays the building owner for the energy the building supplies to the electrical grid is at least equal to the amount the owner pays the utility for energy services and energy used in a year. Carefully examine utility rate structure, as most utilities do not allow any offset in costs for fixed charges and demand charges.

Net-Zero-Energy Emissions: A net-zero-energy emissions building produces at least as much emissions-free renewable energy as it uses from emissions producing resources (i.e. an electric utility)

Net-Zero-Offsite Energy: A building may be considered a ZEB even if 100% of the energy it purchases comes from renewable energy sources, even if the energy is generated off-site.

The logical conclusion is to lean toward the Net-Zero-Site Energy definition because the only way to measure "ZEB" is to look at the energy crossing the site. Definitions that include emission, cost, source, etc. are based on this measured information and then calculations are needed to get to the metric or definition selected. In fact, through an agreement of understanding ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers), AIA (American Institute of Architects), the US Green Building Council, and IES (Illuminating Engineering Society) have chosen site-energy measurements.

ASHRAE's Vision 2020 defines ZEB as one that produces as much energy as it uses when measured at the site.On an annual basis, it produces or consumes as much energy from renewable sources as it uses while maintaining an acceptable level of service and functionality. Per ASHRAE a ZEB can exchange energy with the power grid as long as the net energy balance is zero on an annual basis. ASHRAE recently confirmed with Estes McClure and Assoc that ZEB's, on an annual basis, use no more energy than is provided by on-site renewable energy sources. Remember ZEB's includes only the energy flow of the building, not the overall sustainability of the building. A net-zero-energy building will have a higher first cost. 

The best strategy for a ZEB using ASHRAE's on-site definition is to make the building as energy efficient s one sensibly can, then apply the on-site renewable energy.  For more information you can contact Mike Clendenin at www.estesmcclure.com

Michael D. King AIA

Master Planning

It's the new year and many people and organizations make new years resolutions and set goals for themselves. Is it time for your school district to set their goals and create a master plan for growth? If you haven't been through this exercise maybe its time that you did. So how do you get started? As I have stated before, take time to plan.... you have to plan to plan. It is an investment in time to get organized and pull a team together that can assist you in all the different components of developing a master plan.

So what are the components of a master plan?
1. Demographic Study.
Typically the plan will include a demographic study that will project out a minimum of ten years. The study should outline certain areas in the district that are growing and note any declining trends. Also it should note any special populations that would need to be addressed to accommodate students with disabilities. The study should also review the practical and maximum capacity of your school buildings. This study is sometimes performed by district personnel, but most generally is outsourced to firms that specialize in demographic studies.

2. Building Condition Assessment.
This assessment should review all the components of your physical facilities. Roofing, Mechanical and Electrical systems, handicap accessibility, structural issues, hazardous materials (asbestos, lead paint for example), windows, doors and hardware, finishes such as carpet, vinyl tile and paint, kitchen equipment, and generally the overall condition of the building. It should also assess any historical value to the community. This assessment is usually performed by design professionals, architects and engineers.

3. Educational Adequacy.
This is a review of the building from a curriculum and education point of view. Does the building enable teaching? Are the core elements of the cafeteria, library, gyms, and offices large enough to handle growth? Are the components of the building properly placed, i.e. are quiet spaces adjacent to noisy spaces. Do we have the proper itinerate spaces for the programs that are offered? Is the land area adequate to properly address all the athletic and physical education needs?

4. Site Study
Evaluate sites that may need to be purchased for future growth.

Once all the information is gathered and compiled, you will need to prioritize the list. The school board would then need to adopt the findings and then set out a plan of how to implement the master plan. As in all planning exercises, excellent communications is needed from start to finish. Many districts find it advantageous to engage the community in this process. This allows community members to see the needs that the district has and be able to promote any changes that need to be made.
Realize that the master plan is a fluid document and would need to be updated at least every couple of years. If there is a drastic change in the community, such as the influx of students due to a new industry in the community, the master plan would need to updated appropriately.


   

Choosing Building Materials

With today’s budgets straining many school districts, lowering operational costs in facilities is paramount. When designing a new school or renovating an existing one, material selection can have major impacts down the road when considering the life cycle costs of a building.

1. What materials will extend the life of the building?

2. What materials require minimal maintenance?

3. Can I afford to pay a little more now if necessary to save a lot in the future?

Exterior materials – Brick, stone, or masonry materials are extremely durable and easy to maintain. Pre-finished metal also generally holds up well. At the smaller scale, think about exposed steel columns and lintels. If they are galvanized, they would not need painted every few years. Similarly, anodized aluminum door and window frames would not require paint like hollow metal frames.

Interior materials – There is no end to the options of materials to select from. Evaluate the use of each space to determine where the greatest impact can be made. Higher end materials may not be necessary in the entire building.

Corridors – These are high traffic areas that see a lot of abuse over time. Masonry in these areas have the same benefit as when they are used on the exterior of the building. If the walls are drywall, consider placing ceramic tile, laminate panels or another stronger and cleanable material over the face of the wall. For the floors, if the budget allows, terrazzo will last the life of the building and does not require waxing like vinyl tile does. Other options that would eliminate the need to wax floors could be porcelain tile or solid vinyl tile, among others.

Classrooms – Finishes here can greatly vary depending on how each district uses their spaces. The common choices are vinyl tile or carpet. Tile offers the most flexibility in a space since rugs can easily be placed over them. If there are sinks in the classrooms, this also keeps these areas easy to clean. Carpet can be beneficial, especially in second floor classrooms, to lessen the sound of moving furniture into the first floor rooms below. Extending a higher end finish in these rooms is often difficult to do with many budgets, but the same advantages could be seen here as those mentioned for the corridors.

Restrooms and kitchens – Quarry tile, ceramic and porcelain tiles, and poured quartz flooring are all good options for these spaces. In the facilities we have been working on recently, we are seeing more districts choose the poured quartz flooring because there are no grout lines that will discolor over time. This also provides a seamless surface to clean.

This is clearly just touching the surface of the many material choices that have to be made on each project. I encourage you to talk through the benefits of each material with your architect, keeping in mind the life cycle implications of these decisions.