Photovoltaic Systems

Ann Arbor, Michigan architectural firm A3C has turned its building into a showcase for a number of green building components, and managed to produce a LEED-CI Gold renovation of the existing two-story building while they were at it.  The firm wanted to have a showcase for a variety of green building options, as well as providing themselves with firsthand experience with a number of different systems.

Named the UrbEn Retreat, the third floor addition provides a conference and meeting room. The small space looks out over the roof at the rest of the building which has been turned into a walkable garden space with a number of green roofing systems that make it an extraordinary space in the middle of the downtown.

The roof of the renovation was recently featured in Environmental Design + Construction magazine. Instead of just adding insulation to improve thermal performance and using a single roofing system to cover it, the roof on A3C’s building is an experimental lab to study a variety of roofing options, including both flat roof membranes and vegetated roof systems.

Rather than weighing the options and then choosing and applying a single green roof system, there are several different configurations installed next to one another, including both tray and monolithic installations, and examples of both intensive (shallow growth media) and extensive (deeper growth media) systems included in the mix. Part of the decision was based on what would work structurally with the existing building roof, so the lightest weight vegetated systems were placed where the roof could only support the lighter weight, and deeper, heavier vegetated assemblies were then placed in other areas where there was additional support capacity. A rainwater catchment system is connected to the irrigation system for the vegetated roof, as well.

Further away from the conference room, the other part of the roof (seen upper right on the plan, above) is outfitted with a membrane roof, but here, too, it’s not so simple. Working with faculty from the University of Michigan, temperature sensors were installed under a series of different colored roof membranes, so that the effect of roof color could be measured and compared. Measurements of the temperature under each type of roof, as well as the ambient outdoor temperature are collected at 4 minute intervals throughout the day, to develop a profile of how the roof membranes perform relative to each other, as well as in comparison to the vegetated roof.

The conference room itself showcases a number of features, too. Something that is found in many straw bale construction projects is a “truth window,” a framed opening in the interior wall finish that lets visitors look behind the plaster to see the “truth” that the building is, in fact, built of straw. A3C took a similar approach and has a strip along the south wall of the space showing different kinds of batt insulation installed in the cavities between adjacent studs. Each of these is also outfitted with a small digital thermometer to display the temperature on the wall just to the inside, so that different insulation types can be compared.

Gathering data from actual buildings will help architects and engineers better understand how choices of building systems affect the building, and the benefits and drawbacks to different systems.  And, by allowing the community to use the UrbEn Retreat on evenings and weekends, the space becomes an amenity, as well as a demonstration of the possibilities of green building.

Links:
A3C Sustainability, ED+C.
Images via: A3C,
ED+C, Dave Lewinski.

The USGBC has unveiled a half-dozen new credits for LEED which are being investigated in a pilot program currently underway.  Pilot LEED credits include: Life Cycle Assessment of Building Assemblies and Materials; PBT Source Reduction; Medical and Process Equipment Efficiency; Innovative Ventilation; and Preliminary Integrative Project Planning & Design (2 credits).

Ever since announcing the upgrade of LEED to the new LEED 2009, the USGBC has been talking about putting LEED on a regular cycle of refinement and improvement.  Most current building codes, such as the International Building Code (which serves as the basis for many state and local building codes), Electrical Code, Plumbing Code, and others, are on a regular schedule of updates in order to maintain their applicability.  Likewise, the USGBC has committed to regular updates of LEED in order to keep it at the forefront of green building.

The new credits address gaps in the current LEED system and enable designers and builders to incorporate new methods and improved materials in buildings.  These new credits will be available as Innovation & Design credits for current projects utilizing the pilot credits, but they will also likely appear as part of the next revision of LEED.

The Life Cycle Assessment of Building Assemblies and Materials [PDF] examines materials and building assemblies and serves as an alternative to some of the existing Materials and Resources credits in the current LEED system.  A database will be used to analyze building components, and a scoring system will indicate the number of LEED credits the project can obtain, although under the pilot testing program, it will only be worth a single point.

The PBT Source Reduction [PDF] credit seeks to reduce the use of products containing chemicals that can accumulate in the tissues of living beings (persistent bioaccumulative toxins). This credit addresses reductions of halogenated organic compounds in building materials, including a number of chlorinated plastics and brominated and halogenated fire retardants. These products are typically found in electrical cable and wiring, piping and conduit, interior finish materials such as wall coverings and flooring, and exterior materials such as siding, membranes, doors, windows, and exterior trim.

The Medical and Process Equipment Efficiency [PDF] credit addresses the energy efficiency of equipment used inside a building.  While, in the pilot, this is targeted at medical equipment such as X-rays, MRIs, sterilization equipment, and related items, although it may be extended to other process energy.  Energy using process systems that are contained within a building such as the manufacturing equipment in a factory have been excluded from consideration under previous versions of LEED.

The Innovative Ventilation [PDF] credit allows for a wider range of mechanical or natural ventilation systems which can optimize air delivery.

The Preliminary Integrative Project Planning & Design [PDF] credits attempt to formalize one of the practices that LEED has encouraged design teams to follow, namely an integrative process where the design team works in parallel on the project, and input from numerous disciplines is included at the outset of the project. This would have wider discussions at the early stages of design, when it is easier to revise a design. As the process goes along, it becomes harder to integrate changes, so it is better to get as much discussion early on as possible. This also means the design professionals are working together, rather than a design being handed off serially from one discipline to the next.

Keeping LEED current is important in order for it to remain relevant for green building.  After all, LEED stands for Leadership in Energy and Environmental Design.  Part of the purpose of LEED is to push the industry in the direction of greener and more efficient buildings.  But that is a constantly moving target. What is innovative today may become standard practice in the future. 

Already, under LEED 2009, the mandate for water efficiency has pushed beyond earlier versions of LEED.  In the previous version of LEED (LEED 2.2), there were no prerequisites for water efficiency, and a 20% increase in efficiency (versus a baseline case) was worth one point, while a 30% increase in efficiency was worth an extra point.  Now, under LEED 2009, the 20% efficiency is a prerequisite, meaning that all LEED projects must meet this standard, and the credits are now awarded at the 30% and 40% thresholds.

LEED has undoubtedly been at least partly responsible for encouraging this shift in the industry.  Plumbing equipment manufacturers have caught on, and low-flow fixtures are now readily available — often at little or no increase in cost.  Water efficiency has become more commonplace.  Now, like water efficiency, these pilot credits will help push the industry toward a greener direction in new and important areas. 

More information about LEED credit piloting is found in Appendix 1 (pp 21-2) in Foundations of LEED [PDF].