High performance buildings should be energy efficient

Filed under: Focus |

High performance buildings can give owners a competitive advantage in the marketplace by increasing cash flow, improving capital assets and providing a high-quality environment that satisfies occupants. Energy efficiency is one strategy to designing and constructing a high performance building. High-performance buildings can achieve higher occupancy, improve productivity and create higher revenues in the marketplace.

A high performance building starts with a whole-building design approach. This approach is an integrated approach that examines all the elements of the building to optimize energy performance. Energy efficient buildings use less energy for heating, cooling, lighting and equipment. A successful design requires the active participation of the entire design team early in the design. The team is usually comprised of the following specialties: general architecture, HVAC, lighting and electrical, interior design, commissioning, and landscape design. Energy use and cost calculations are done very in early in the design and throughout the design to inform the team of the impact of the design choices on energy use such as the building orientation, envelope, mechanical and electrical systems, and lighting options.

Siting concerns include the building orientation and access to transportation and major utilities. The energy efficient site strategies include aligning the building along an east-west axis to maximize the southern exposure and a landscaping design that maximizes the effects sun in both the summer and winter. Landscaping can also help deflect winter winds away from the building. All of these strategies lead to a climate responsive design.

The building envelope consists of doors, windows, walls, foundation, roof, and insulation all the components that separate the building interior from the outside. Building envelope strategies can reduce the space heating and cooling requirements thus reducing energy costs over the life of the building. Energy efficient windows can be cost-effective when they are designed and placed to provide the multiple benefits of daylight, minimize summer-heat-gain, maximize passive solar heating and provide a view to the outside. Our Colorado climate is conducive to passive solar strategies that use thermal mass to maintain temperatures based on the season. This strategy can lead to downsizing of the HVAC system which results in a first cost savings. It is important to incorporate passive solar strategies early in the design to achieve the most cost-effective solution.

Windows are an integral part of daylighting design. Daylighting can save energy costs when properly designed and effectively integrated with the electric lighting system by off setting electrical lighting requirements. Daylighting has synergies with other building components by reducing cooling requirements and improves occupant comfort. Recent studies of schools show improved student performance in daylit schools. Other lighting design considerations include setting performance requirements such as using less than 1 watt per square foot and the appropriate use of ambient, task and accent lighting to optimize energy use.

Heating and cooling systems use the 50% of the energy in a building. High performance buildings using an integrated design process can result in a downsized HVAC system compared to a traditionally designed building. This downsized system is a first cost savings but also a savings over the life of the building because the system is right sized. HVAC system design considerations include energy efficient equipment and energy recovery systems that pre-heat or pre-cool outside air. System and components need to be evaluated for long term benefits which goes beyond design for solely based on the peak load but rather at part load conditions. Part load is where the equipment operates most of the time and designing for part load efficiency provides the owner with savings over the life of the building. Building Automation Systems (BAS) can control systems based on occupancy and schedule. Control strategies can also be optimized during occupancy to reflect actual use.

Including a commissioning professional on the design team can provide the owner with the training and testing needed to verify that the systems meet the energy efficiency design intent. Commissioning is a system based process that helps to verify that the energy using systems work together effectively and efficiently. Commissioning involves documentation, testing and training on specific building systems. During occupancy a comprehensive operations and maintenance program is important to achieve continued energy savings through out the life of the buildings.

Buildings consume about 40 percent of the America’s energy annually and in 1999 commercial buildings used 5,300 trillion Btus (see Figure 1). High performing buildings using an integrated design team approach are achieving a 30 – 50 percent energy cost savings compared to a traditional design. A recent report “confirms that minimal increases in upfront costs of about 2 percent to support green design would, on average, result in life cycle savings of 20 percent of total construction costs – more than ten times the initial investment.” This October 2003 report “The Costs and Financial Benefits of Green Buildings” was for the California’s Sustainable Building Task Force.

Tia Heneghan, LEED” AP manages the Corporate Sustainable Division with Sebesta Blomberg. Ms. Heneghan has been actively involved in environmentally responsible design for over 20 years, and serves as a Sustainable Design Consultant for the Pentagon Renovation.