Lessons Learned – 749 University Row
Variable Refrigerant Flow. Tuning immediately following start-up required a bit more time and more parties than planned. The thermostat is deceptively simple, but actually can require significant tuning.
Due to the newness of the system type, the contractor had to rely on the vendor for the trickier tuning exercises. Finally, after design was essentially complete, it was learned that a bank of condensing units serving a single tenant was not capable of modulating the water valves to allow for variable flow based on load.
As a result, energy used for pumping power for the building was significantly higher than predicted. This lack of modulation needs to be addressed by the manufacturer.
Stairwell and Elevator Design. An inviting entry stairwell encourages the majority of occupants and visitors to use the stairs instead of the elevators, which are located behind a row of doors. As a result, elevator motive energy use is low. However, unfortunately the elevators were not selected with occupancy controls, so lights and fans still use energy when the elevator is not in use.
Dealing with Orientation. The building is located on a street that runs approximately 38° off of east-west—not the ideal east-west orientation that usually drives high performance. With the building forced into this position by its context to the street, the team paid careful attention to solar control via overhangs and solar shades on the outside, and diffuse daylight-emitting roller shades on the inside. Significant effort can be avoided with a better orientation, but when forced, solutions are available.
Building Automation System. The VRF uses proprietary controls, requiring a second, higher-level BACnet compatible building automation system (BAS). As a final layer, the BAS also feeds a building dashboard where performance can be seen by the public via the internet.
Not all buildings should pursue this depth of control capability due to its associated costs and complexity. But when this level of functionality is needed, this type of control system hierarchy will often result with VRF systems. If it is done this way, the structure—including naming—requires significant forethought and the controls contractors will not have time to give it that forethought or come up with a robust naming hierarchy in the field.
High Performance with Multiple Tenants. Having multiple tenants in the building does add additional complexity to ensure the building will perform, beyond the basic fact that each tenant has widely varying needs and operations. M&V was made more complex with multiple meters. The M&V consultant set up points of contact with each tenant through the owner at the time of move-in, and explained the high performance goals of the building and the need for utility billing information.
Balancing and commissioning agents found the staggered move-in dates over a nine-month period to be challenging. Each time a new tenant moved in, system balancing and control tuning devolved. These agents initially tried to conduct significant operations after the first couple of tenants, but ultimately saved the most thorough activities for after the final tenant was in place.
Common Area Thermostats. Occupants were locally changing the setpoint on common area thermostats. These thermostats had to be locked out.
Costs and Benefits of High Performance Building. Building owner Paul Lenhart summed up the business impact of sustainable building. “I'm an advocate for the construction of high performance buildings,” he said. “I feel they are one more positive legacy we can leave and they point to good stewardship of limited resources. High performance buildings are also good for business and offer competitive advantages in the marketplace [due to faster leasing].
“As a bonus, as high performance building materials and technologies are used more frequently, costs will inevitably go down, making sustainable buildings more affordable and widespread,” he said.