High Performing Buildings - Fall 2011 - (Page 29)

among sustainable features by asking a simple question: “Will the anticipated annual savings of a particular feature equal or exceed the increase in municipal bonding costs associated with its design and construction?” If the answer was “yes,” the feature was approved. Because the cost premium for high-performance equipment generally increases with each increment of performance improvement, this rule kept the governing body from investing in performance improvements beyond the point of diminishing returns. A geothermal system was rejected because it failed to meet the savings/costs criteria. The rooftop photovoltaic array was initially rejected for the same reason. However, after the township received a substantial grant toward its cost, the economics became sufficiently favorable to justify its inclusion. An independent life-cycle cost analysis, done by Rutgers Center for Green Building after construction was completed, shows that the Police and Court Building is slightly less expensive on a life-cycle basis than the conventional, budget alternative as modeled in the building’s LEED submittal. Solar renewable energy certificates are a crucial Lessons Learned The tighter the building envelope, the more sensitive building performance is to ventilation air volume. Although the building is occupied round-the-clock, the number of occupants ranges from as few as three at night and over weekends, to as many as 150 or more during court sessions, with an average of around 25. As with many high performance buildings, this one has minimal uncontrolled air infiltration. A network of carbon dioxide sensors provide real-time indications of air quality from which ventilation air requirements are calculated. The design was based on 20 cfm/person, and assumed simultaneous and full occupancy of each space. The Bms responds to the building’s widely varying occupant loads by continuously sensing and calculating the volume of fresh air actually required. After occupancy, we learned that the amount of air delivered was extremely sensitive to the response of the Bms to changing occupant loads. Although the specified operations sequence required it to be appropriately programmed, our analysis of the building’s actual gas use revealed that the volume of air being delivered (and conditioned) was substantially higher than necessary for the given number of occupants. To ensure smooth and uninterrupted operation, program the Bms to respond gradually to changes. Another feature of many high performance buildings is that chilled water temperatures vary in response to load. However, to prevent freeze-up and shortcycling of the chiller, the Bms must be programmed to modulate chilled water temperature gradually in response to changing demand, just as the cruise-control system in a car responds gradually to changing grades. While troubleshooting the cooling system after start-up, our engineers found that the setpoints and equations with which the Bms had been programmed required fine-tuning to dampen its response. don’t underestimate the risk of glare from large windows, even when outfitted with lightshelves. in spite of using vision glass with a low visible light transmittance and shading it with lightshelves, some occupants with desks near windows complained of glare. This was addressed through the addition of roller shades in appropriate locations. Avoid large pressure differences. in the firing range, failure to turn on the exhaust and makeup fans simultaneously produced such a large pressure differential that it was impossible to open the door to enter or leave the area. To correct this, the exhaust and makeup air fans had to be interlocked. design to accommodate growth and change. To reduce the cost of providing public services, maplewood explored, during design, the feasibility of sharing its court operations with those of neighboring south orange (the municipality with which it already shares its school system). south orange showed no interest at that time. However, soon after the building was completed, by which time the recession was under way, south orange reversed its decision. since the beginning of 2011, both townships have been operating their municipal courts out of this one building, to their mutual benefit. The building proved flexible enough to accommodate this change even though it was not designed for this purpose. Fully investigate the sustainability implications of design changes prior to implementation. during construction, the municipality requested that the species of wood veneer used in the courtroom millwork and paneling be changed. it was not confirmed until much later that the new species was not available from certified forests. Had this been known at the time, the change probably would not have been approved. Consider not only the performance of the building envelope, but also its form. The gains and losses of energy through the building envelope are a function of its resistance to heat flow and of its total area. Building codes and leed address the thermal resistance of the building envelope, but they do not address the building’s surface area or its ratio of surface area to volume. As a result, a building with an inefficient form but a highperformance envelope is looked upon more favorably than a compact building (enclosing the same interior area) having a slightly lower r-value, even though the latter may have much lower aggregate skin losses than the former. if the goal is to save energy, the codes and rating systems need to address the form factor, or ratio of surface area to volume. With its simple form, efficient internal layout, and tight floor-to-floor heights, the maplewood Police and Court Building has a low ratio of surface area to volume. A building’s sustainability implications are not limited to those that fit on its site. As explained earlier, coordinating the site plan of this project with the site plan of the neighboring church resulted in benefits to both projects. sharing the church’s parking yielded a host of environmental benefits. Finally, sharing designated facilities in this building with community groups, and sharing its municipal court with a neighboring municipality, help provide public services more cost-effectively and sustainably. Fa l l 2 0 1 1 HigH PerForming Buildings 29

Table of Contents for the Digital Edition of High Performing Buildings - Fall 2011

High Performing Buildings - Fall 2011
Commentary
Contents
Manitoba Hydro Place
Maplewood Police and Court Building
Omega Center for Sustainable Living
Dockside Synergy at Dockside Green
Golden Hill Office Center
Letters to the Editor
Products
Advertisers Index

High Performing Buildings - Fall 2011