On vacation in Hawaii recently (yes, life is really tough for us consultants), I had the opportunity to visit the Hawaii Preparatory Academy’s Energy Lab, the first classroom and the third building certified under the Living Building Challenge Program.
I realize that when you live in paradise, it’s easier to build a net-zero energy and net-zero water use building, but the Energy Lab serves a greater purpose and, for those institutions that have the opportunity (and the money) to create facilities such as these, they can really help to advance sustainable building.
The most interesting thing I gleaned from my visit was how engaged the students are in efficiency and building technology. These kids are learning about how buildings operate, and are in the process of auditing the rest of the campus to recommend improvements to be made.
They are becoming what someone recently described to me as “sustainability natives.” Those who become architects, builders, or engineers will, unlike most current practitioners, have sustainable principles ingrained in their thinking. Today, green building practices are often an afterthought to most professionals. But as more people grow up understanding the value of high-performance construction, sustainability will be fully integrated into their thinking and their work when they become practitioners.
Geeking out in a living building
Luckily, the day I was able to visit, Bill Wiecking, the lab director, was available. Bill spent quite a bit of time showing me around. I was a bit challenged to keep up with his rapid-fire explanations, but learned about many of the interesting features included in the building, as well as some of the challenges that they ran across.
Probably the most interesting feature (to me, at least) was the solar thermal cooling system. Because the site has a dependable cycle of the diurnal temperature change, liquid that is pumped into the solar panels is cooled at night, stored in tanks, then run through fan-coil units to provide air conditioning during the day.
Their passive ventilation system is elegant in its simplicity: manual louvers at waist level combine with electrically operated ones at the top of the building. Air flows up along the roof slope, limiting the amount air movement in the room while still providing necessary ventilation. The bottom louvers have a habit of closing on their own, so the students created simple blocks of wood to hold them open.
The building is equipped with indoor and outdoor CO2 sensors to determine when ventilation is required. Instead of basing their ventilation on absolute CO2 concentrations indoors, they compare inside to outside to identify when indoor concentrations are high enough for ventilation. They originally ran their ventilation automatically, but reverted to manual controls to avoid over- or under-ventilating.
Everyone has problems
Bill and I did a bit of commiserating about our experiences fighting with mechanical engineers about HVAC system sizes, and trying hard to get contractors to do what you really want from them.
He pointed out a set of ¾-inch copper lines that were installed instead of the 1-inch lines specified for the thermal cooling system. The smaller lines didn’t work and were ultimately abandoned in place when the properly sized ones were installed.
Design and construction of the building were challenging, and building operation has been challenging, too. Doors to the offices and workrooms with individual minisplit air conditioning systems (used primarily for dehumidification) are often blocked open with the AC running. Behavior problems never stop being an issue, even in the best buildings.
The CO2 sensors are costly and require frequent replacement. And one thing I noticed was the significant quantity of cobwebs throughout the building. Spiders must love how the passive ventilation brings loads of insects right into their webs. While they don’t cause any problems, the webs detract from the look of the building. Cleaning them is likely an ongoing project, sort of like painting the Golden Gate bridge.
Location, location, location
Bill mentioned that many visitors to the lab talk about replicating the building in other regions, not realizing that the details of this building (like those of most buildings) are climate-specific. While I love the passive ventilation, the louvers don’t provide much in the way of insulation or air sealing, so they wouldn’t be very useful in most climate zones. The solar thermal cooling is a great idea, but it will only work in certain climates where there is enough of a daily temperature swing.
This building is a great experiment, and the kids who use it are learning amazing lessons that will stay with them throughout their lives. It is not a building type that will work in most climates, but as a research facility, home to many building science experiments, and an example of seriously forward thinking, it is a great model for schools and professionals to aspire to.