High-Performance Buildings

Change often happens with dedicated individuals and organizations showing leadership. In this case a team of professionals designed and constructed a high quality, high-performance building at 749 University Row in Madison, Wis. The building was designed with quality, comfort, energy efficiency, and sustainability in mind. The result is a notable office space where both the developer and tenants find value.

The office building is part of a new development located on an infill site. Existing unusable buildings were largely recycled when demolished. A holistic approach to energy reduction was practiced. This included the energy used in the building as well as embodied energy and transportation energy. The facility allows for multiple commuting options: heated bicycle parking and showers are available, the building is within walking distance of numerous bus routes, and car parking is shared with a nearby apartment building. Facility design allows tenants to limit their use of energy and water resources significantly.

To pass on the lessons we learned in the design of this building, we have created seven vignettes that detail key features, illustrate our collaboration efforts, and provide highlights about the completed building. Much more information is found by clicking on the link corresponding to each summary listed below:

• High-performance multitenant office buildings
• Façades for cold climates
• Heating and cooling with a ground coupled variable refrigerant flow system
• Demand control ventilation
• Advanced lighting and day lighting
• Refining lighting systems: task tuning for lighting
• Including an efficient enclosed garage

High-performance multitenant office buildings

Delivering high-performance, multitenant commercial buildings is a challenge because of the complexities involved. The developer, including investors, want to appeal to the market yet manage rental rates—many prospective tenants want high quality, low costs, and sustainability. Further, a building developer can't construct a high-performance building simply by purchasing high-performance technologies, there needs to be expertise in the design effort. Finally, building owners don't often directly benefit from a high quality facility—the tenants do. As a result of these constraints, the majority of high-performance buildings today are either public- or owner-occupied. Nevertheless this building and an increasing number like it are demonstrating an alternate path to meeting the market need for high-performance buildings everybody is delighted with.

Façades for cold climates

In essentially every climate, good façade design begins with good glazing design. In the upper Midwest, limiting glazing area is important because even the highest performing glazing has a much higher U-value (U = 0.2–0.3, R=5.0-3.3) than a typical wall assembly (U < 0.064, R>15.6). In addition in the summer large areas of poor glazing produce glare and allow significant amounts of solar heat into the space, contributing to peak cooling load. At the same time, people enjoy ample daylight and access to outdoor views. Optimal glazing design, therefore, is a balancing act that provides adequate daylight, minimizes direct sun exposure and reduces energy use. This vignette describes glazing performance parameters including: placement, sizing, heat gain, heat loss and day lighting. Glazing selection provides the foundation for a well-designed wall assembly and rounds out the façade for a well-insulated and well day lit building.

Heating and cooling with a ground coupled variable refrigerant flow system

Variable refrigerant flow (VRF) is a heat pump technology which can contribute to a high-performance HVAC system and building. Improvements in refrigerants and continued interest in energy performance have increased its use in the United States. Many people are familiar with ductwork that moves air for providing heating and cooling. Likewise, VRF systems use piping and a refrigerant to provide heating and cooling. Energy is saved due to the variable speed of the compressor, the distribution of energy-dense refrigerant as opposed to air, heat recovery between zones and precise zone control.

In the cold climate of the upper Midwest, air-source VRF systems have difficulty meeting heating loads when the outdoor temperatures drop below -5ºF. The consequences can be oversized equipment which adds to system cost or installing supplemental heat which adds to operating costs. A VRF system can be connected to a boiler and cooling tower (water loop) or, for even higher performance, an in-ground heat exchanger (ground loop). 749 University Row uses a ground coupled heat exchanger for heat rejection and source.

Demand Control Ventilation

Buildings require a certain amount of ventilation, or outdoor air (OA), in order to ensure quality indoor air. Typically the outdoor air amount is calculated using the building's maximum occupancy. However buildings are rarely at full capacity; OA is oversupplied; and unnecessary money is spent to heat and cool the excess OA air. Demand-control ventilation (DCV) modulates OA based on the number of people in the building thereby saving energy and money. In addition to spaces where energy codes now require DCV, there are other cost effective ways to use this innovative technology. This vignette discusses OA control methods, best spaces for applying the technology and provides examples of cost savings from its use.

Advanced lighting and day lighting

Over the last decade building designers have been returning to the centuries-old practice of lighting indoor spaces using natural daylight. While building energy codes now require basic day lighting controls on lights adjacent to windows, there are also more advanced approaches. To ensure optimal use of day light as well as provide occupant comfort including glare control and energy savings, complete a daylight analysis early in the design process. The design should consider building orientation, skylights, light shelves, overhangs, glazing properties, and glare. Keep in mind that while glare can be minimized with interior screens, this does not reduce the cooling load. Additional advanced options include setting target light levels, additional controls, and very importantly: commissioning.

Refining lighting systems: task tuning for lighting

The task of a lighting designer is to design a lighting system that provides just enough light for a building's occupants to conduct their daily tasks. For instance, reading a book typically requires more light than walking down a hallway. Design complaints are avoided by over lighting. Today's dimmable lighting technology allows operators to reduce over lighting by task tuning the lights. That is, light levels are adjusted so that luminance is appropriate for the activity. Task tuning has the greatest potential for energy savings in spaces with long hours of operation; lighting systems that have never been commissioned; and systems designed by contractors. If dimmable lighting is already in place, task tuning can have a payback as short as 0.5 to 1.1 years.

How to make even an enclosed parking garage high performance

Underground enclosed parking garages provide several environmental benefits over surface lots. There is efficient land use, no storm water runoff and no contribution to the heat island effect. An underground enclosed parking garage does require mechanical ventilation and more lighting than a surface lot. However, careful design and control of these two systems can nearly eliminate the already minimal energy footprint of the underground garage. Technology improvements options encompass bi-level LED lights with occupancy sensors and demand control ventilation. Heating energy can be minimized ever further by using a high efficiency heater and/or heating outdoor air using a lower temperature heat source.

This project put together a high-performance design team to make a high-performance building. They solicited potential tenant input before design began and worked collaboratively while paying attention to the many details. The complete design team is listed below.

• Owner/Developer: Krupp General Contractors and University Crossing Investors
• Architect and Sustainability Coordinator: Potter Lawson
• Energy Consultant: Slipstream, formerly known as Seventhwave
• Mechanical Design and Contracting: General Heating and Air Conditioning
• Electrical Design and Contracting: Specialized Electric (with individual lighting designers per tenant)
• Civil Engineering: D'Onofrio Kottke and Associates, Inc.
• Commissioning: Sustainable Engineering Group