Implementing Building Envelope Improvements
- By Rob Winstead, Rich Corona
- June 1st, 2011
When it comes time to modernize an existing school, districts often are faced with the decision to renovate or rebuild. While a new facility may be the most large-scale way to bring a school completely up to date, many districts simply do not have the budget. Renovations may seem overwhelming at first, but by focusing on the building envelope, districts can make simple, straightforward upgrades that result in a more environmentally friendly building, lower energy costs and improved function in other systems.
Evaluating the Existing Facility
Once the decision is made to renovate, assessing the existing facility is key to understanding what renovations need to be made, as well as prioritizing the opportunities for upgrades. To do so, architects, mechanical engineers and electrical engineers should collaborate to approach the facility assessment from all angles.
“The facility assessment is a crucial part of the renovation process because it helps us understand our clients’ needs and tailor renovation recommendations to meet those needs,” said Lee Andrea, principal at SHW Group, one of the nation’s largest educational architectural and engineering firms. “Our architects and engineers work collaboratively to determine what areas of the building envelope and mechanical and electrical systems present the greatest opportunities for renovation at the highest return on investment.”
Prior to performing the physical evaluation, the architect and engineers work with district administrators, faculty and staff to assess how the building performs in its current state and determine what immediate changes can be made from an operations stance to improve the building’s performance. Many times, even the simplest changes can make a significant impact on energy savings. It is also important to understand how the building functions on a day-to-day basis so architects recommend changes that will provide a cohesive transition for user groups into the updated facility.
When the architects and engineers have a solid understanding of the building operations, they can move forward with the hands-on facility assessment to evaluate the building envelope, mechanical systems and electrical systems for both simple and large-scale upgrade opportunities. Even when focusing on building envelope upgrades, it is important that all systems are evaluated to understand how each affects another’s energy usage.
Post-evaluation, the architects and engineers collaborate to perform energy modeling on the potential updates and compare it with the school’s most recent energy bills. By looking at the key components one-by-one, they complete a life-cycle analysis that yields the projected energy savings. The facility assessment and resulting life-cycle analysis provides administrators with the information to pick and choose which updates they would like to include in the overall renovation based on the upfront cost, projected energy savings and long-term maintenance costs.
Districts are not the only groups seeing the value in facility assessments. SHW Group and consultant, Strategic Energy Solutions, recently partnered with the state-funded Energy Efficiency Program, which provides technical assistance to public and private K-12 schools in the state of Michigan to develop a detailed plan for energy efficiency upgrades to their building. They conducted a comprehensive energy audit of Airport Community Schools’ Wagar Middle School building, which identified two types of recommended improvements to the building — low- or no-cost behavioral, operations and maintenance improvements and energy conservation measures that require financial investment. In all, these recommended upgrades would yield significant annual energy savings with a quick payback; savings from improvements would pay for the initial investment in eight years or less.
“Information learned during the energy audit has been a great tool for our school district as we continue to focus on finding ways to reduce energy use at Wagar Middle School and throughout the school district,” says Airport Community Schools’ Maintenance director, Dan Fahnestock. “The audit also supported our fears regarding the amount of energy we were wasting and has allowed us to focus upgrades on those that will greatly reduce our energy use in the building.”
Biggest Impact, Lowest Cost
Following the comprehensive facility assessment, districts must decide what renovation recommendations they would like to pursue. The building envelope is one area that districts can focus renovation efforts on, especially if they are looking to significantly improve the building’s energy performance. Envelope upgrades can be implemented as individual projects or as part of a large-scale renovation, and have a direct impact on energy savings and generally a short-term payback in terms of energy savings ersus upfront cost. Additionally, building envelope improvements may help reduce the energy costs of existing or upgraded mechanical HVAC systems and combining envelope and HVAC improvements may help both upgrades achieve less than an eight-year payback.
Of all the building envelope upgrades, windows have the biggest impact on energy savings. There are many different ways to approach window upgrades that can fit within a range of budgets. Replacing old windows with energy efficient ones is the most basic way that schools can upgrade their window systems. Many different kinds of windows with various glasses and tints are available, and schools can decide on the appropriate window based on each individual room.
Making renovations to allow for daylight harvesting is another way in which districts can update window systems. Daylighting promotes the use of natural light to achieve the desired illumination level without compromising visual comfort. By evaluating the building orientation, solar exposure, room and window geometries, glare control and heat gain management, architects can design a plan that will promote daylighting and work with the existing facility.
Furthermore, daylighting not only decreases energy costs by minimizing the need for electric lighting, but it also improves the learning environment for students. In fact, a study by the Heschong Mahone Group found students with the most daylight progressed 20 percent faster in math and 26 percent faster in reading than students with the least daylight.
Along with the windows, the roof is another envelope feature that has a great effect on energy savings. Roof renovations can range from adding insulation to changing the roofing surface to completely replacing the roof. The dark-surfaced roofs common in many older schools absorb solar energy, thus increasing the need for air conditioning and subsequent energy usage. Replacing these dark roofs with a light colored, reflective surface helps the light bounce off the roof, decreasing the HVAC system usage and thus, energy costs.
SHW Group took a unique approach to roof replacement at Northeast High School in Pasadena, Md. Because renovation plans called for both roof upgrades and an updated storm water management plan, SHW Group saw the opportunity to integrate the two by implementing a rainwater harvesting system within the roof renovations.
The school’s original storm water management plan included expanding a nearby pond and installing a four-foot-deep retention basin under a new athletic field to accommodate storm water runoff. SHW Group instead suggested that rainwater harvesting would subtract the roof of the existing building and proposed additions from the total impervious area, greatly reducing the storm water runoff generated on site. Instead, the school could collect rainwater off of the roof and store it in an underground cistern. The stored water then could be piped back into the building to be used for non-potable applications like toilet flushing and field irrigation.
The resulting rainwater harvesting plan eliminated the need to expand the pond, which saved the district $300,000 in upfront costs and decreased the campus’ environmental footprint on the nearby Chesapeake Bay. Furthermore, the system will save the district a projected $1.7 million in water costs over the lifetime of the facility. Further, adding insulation and a reflective white membrane is predicted to save the school approximately $7,000 per year in energy costs. The reflective surface also maximizes the daylight harvesting potential of the new roof monitors and clerestories. This illustrates how a thoughtful and holistic approach to a single envelope improvement can have multiple benefits.
“Integrating roof replacement and a rainwater harvesting system allowed us to not only save money upfront, but in the long run as well in terms of both energy and water bills,” says Alex Szachnowicz, chief operating officer for Anne Arundel County Public Schools. “Furthermore, these renovations decreased the school’s impact on the surrounding environment, providing a 21st-century facility that takes into account the needs of our students, teachers and environment.”
Approaching renovations with an initial comprehensive facility assessment followed by targeted building envelope upgrades allows districts to make improvements that significantly impact the buildings’ energy performance at a relatively quick return on investment. In turn, the completed facility provides an environment that is highly conducive to learning as well as healthy for students and teachers.
Rob Winstead, AIA, LEED-AP, is a principal and the director of Sustainability at SHW Group. He is a leader in the national conversation pertaining to sustainable design, in general, and high-performance schools, in particular.
Rich Corona, PE, LEED-AP, a principal engineer at SHW Group, has over 20 years of experience in mechanical, electrical and plumbing systems design for higher education facilities.