Monthly Archives: December 2009

A Database, and a Building, to Watch

The US Department of Energy High-Performance Buildings Database is an intriguing source of information for green design. On the positive side, it presents design intents (including architectural vision) and performance strategies for 125 progressive buildings, as well as links to sources and contacts. On the other hand, many entries dwell on the acquisition of LEED points, present only modeled performance “data”, gloss over any interesting problems that may have arisen, and show no evidence of post-occupancy investigation.

At least two of the buildings in the list, however, present honest, detailed, useful accounts of their experiences: the Adam Joseph Lewis Center for Environmental Studies at Oberlin College and the Environmental Technology Center at Sonoma State University. Interestingly, these are both university buildings dedicated to environmental studies; with luck, more submissions will follow their examples! Here is a bit about the first one.

Adam Joseph Lewis Center for Environmental Studies at Oberlin College. With a design team led by passionately idealistic professor, David Orr, equally visionary architects at McDonough + Partners, and outstandingly generous donors in the Lewis family, this building was privileged from the beginning. Few of its contemporaries would be able to support a living machine, for example! But many of its features are widely relevant:

  • elongated form to maximize permeability to light and air
  • east-west orientation to simplify shading
  • passive solar heating design incorporating thermal mass (not a simple choice in a cold winter climate)
  • radiant heating in large open areas, such as the atrium, that have high infiltration
  • a geothermal heat pump
  • daylighting with photosensors to dim electric lights
  • an outstanding low lighting power density of 0.9 W/sf
  • automated operable windows for passive ventilation and cooling
  • demand (CO2)-controlled ventilation to save fan energy
  • very expensive highly-insulating glass
  • a stunningly large 4,000sf photovoltaic array (an imperfect answer to the ideal of “sustainability”)

All of these features have been debated in projects I’ve worked on in the last year: they are gradually entering the mainstream, and owners and architects are in need of solid precedent studies.

The exceptional part of the Lewis Center effort is the commitment by both Oberlin staff and students and NREL scientists to evaluate the performance of systems in their contexts, to make both big changes (e.g. replacement of the original electric boiler with a ground-source heat pump) and small ones (controls adjustments) and to track the effects of changes. An excellent real-time display is provided on the Oberlin website, and field work results by Paul Torcellini and colleagues at NREL are also now a public document.

So: how well does this building perform? The answer is: quite well! It has an EUI of about 32 kBtu/sf-yr, met entirely (on an annual basis) by the PV array. This is about 1/3 of the EUI of other Oberlin buildings. Is it “really” net-zero? Some purists argue persuasively that the point of a net-zero building is not to offset energy use with enormous arrays of silicon wafers, glass, and metal. We’re working on a net-zero K-12 school now that’s seeking the same vast-PV solution, understandably – getting heating loads down, after a point, is just really, really hard. In any case, Oberlin has taken a fantastic step forward for all of us – not only by creating this progressive building, but by sharing their experiences, good and otherwise, with all of us.

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What does building performance “research” mean, exactly? (part 2)

The Scandinavian hospital study illustrates several contributions that building research offers, that energy modeling, commissioning, and system monitoring cannot:

1. Understanding of design intent

The vision of the design team – owners, stakeholders, architects, and engineers – has a permanent impact on the energy performance of a building. Siting, geometry, orientation, envelope materials, organization of the program, spatial configuration, and environmental control system choices all reflect this vision, tempered by constraints of time, money, and building codes, and all have substantial impacts on the energy needed to heat, cool, light, and ventilate the building.

The effects of these key performance-affecting decisions are so decisive, and so long-lasting, that we must understand the forces that shape them in the design process. This element is therefore a cornerstone of building performance research.

2. Systems-level analysis

Buildings operate as complex systems of people, machines, structures, and climates. Since these elements affect building performance as an interacting set, a clear understanding of building performance necessarily requires investigation into the operation of the system as a whole. Energy models do simulate buildings as systems, but their best role is to inform decisions among a limited set of design alternatives; they are definitely not diagnostic tools. To understand the operation, and especially the malfunction, of a real building requires field investigation.

Revealing unexpected activities of occupants, and understanding the origins of these activities, is an especially important aspect of field research. Unprogrammed use of spaces, manual overriding of system controls, and propping openings open or closed are just a few ways that occupants can unwittingly diminish the energy performance of their building; tracing these to their motivations, and then to concrete aspects of the building design or operation, is an essential component of systems-level building research.

3. Pattern discernment through comparison of multiple buildings of a type

Each building is substantially unique: despite common elements, a particular assembly of spaces, materials, climate, program, and occupants is rarely duplicated. This complicates efforts to determine which performance strategies work well, and which don’t, in a particular building type. Yet, as the Scandinavian hospital study shows, patterns do emerge when enough examples of a type are compared.

The seeking of patterns among multiple examples of complex systems has excellent precedents in field ecology (see work by E. Odum and J. Lovelock) and in architecture (C. Alexander, A Pattern Language). Their field techniques and analytical tools are directly applicable to building systems, as well, and should inspire us toward a “comparative building ecology” that illustrates performance patterns, in their contexts, robustly.

4. Controlled experimentation

Although every building is an uncontrolled experiment, some controlled experiments can be conducted within a building, nonetheless. Energy use of analogous spaces that differ only in occupancy or equipment can be compared; conditions in individual spaces can be tracked through varying seasons; passive airflow paths can be obstructed or cleared; light shelf sizes and angles can be varied; setpoints and schedules of mechanical systems can be adjusted, for example. While such adjustments are often undertaken by facilities managers, rarely are the results of individual changes tracked over time to yield meaningful information. Such experiments might also be simulated with models; an intriguing document by the New Buildings Institute presents such analysis for large buildings. Given the limitations of models, however, the realm of controlled experimentation remains an important one for teasing apart relationships among spaces, people, and environmental control systems in real buildings.

5. Publication

The ultimate goal of pure research is to publicize the results, so that a wide audience can learn from them (where “publication” includes meetings, talks, discussion forums, and websites as well as design and science journals). In contrast, commissioning reports and building energy models are private documents; indeed, building designers and owners are understandably reluctant to publish evidence of performance below expectations.

At the same time, the disclosure of design decision pathways, model predictions, operational realities, and performance outcomes would help future design teams immensely. This, therefore, is the most important of the unique contributions that building performance research has to offer: the provision of reliable information, obtained through rigorous investigation and experimentation, unbiased by financial or legal interests, in straightforward, accessible forms with the strength to change common practice.