Langara College | Building Deep Retrofit

Challenge

Originally built in 1969, the oldest building on Langara’s Vancouver campus, ‘A’ Building, was also the least energy-efficient. It had double the energy intensity compared to other buildings on campus. In fact, the ‘A’ Building consumed nearly 75% of total campus energy use. From a strategic energy management perspective, this building’s energy intensity was an excellent target for meeting the college’s ongoing energy savings goals.

Solutions

Following Prism’s assessment of mechanical and electrical systems completed in 2014 (and updated in 2016), most of the equipment in the ‘A’ Building was considered end-of-life. To understand and prioritize upgrades, Prism evaluated options and energy savings potential for a renewed HVAC system.

The original constant volume reheat system serving 75% of the building was upgraded to a variable volume reheat system. This $1.8 million-dollar project upgraded the components of the existing air handling units and replaced constant volume reheat coils with variable air volume reheat boxes to reduce the air flow to the zones when they are unoccupied or partially occupied. Advanced demand-based controls were integrated to maximize energy savings. This construction was completed with minimal disruption to staff and students since classes were in session.

A thorough review was conducted for each space to minimize the energy consumption of the upgraded ventilation system. Each zone has dedicated temperature, occupancy and carbon dioxide sensors integrated into each classroom to ensure acceptable ventilation air levels are provided by the ventilation system. This also reduced excessive energy consumption by minimizing outdoor air and energy usage by the supply fans.

A distinguishing feature of this project is the use of a fan array and reconfiguration of the air handling unit (AHU). The original four vane axial fans, external to the AHU, were replaced with a fan array within the AHU consisting of a total of 14 integrated fans. The original supply air system had a total capacity of 143,000 cfm and 6” S.P. and would run at a constant volume. The 14 smaller fans operated at 10,000 cfm each and can run partial loads as required by the upgraded variable volume distribution to optimize energy consumption.

Maintenance has also been reduced with this renewed system. The fan wall diversifies the risk of equipment failure and makes the entire supply air system more reliable. Should one fan fail, the failed fan is isolated. The remaining fans can provide the required airflow for the building.

Reducing carbon footprint through innovative practices

Results

The new HVAC system has been operational since March 2018.

Submetering is currently being monitored on Building ‘A’ and preliminary data is being obtained. The original Building Energy Performance Index (BEPI) for Building ‘A’ in 2014 was 39.7 ekWh/ft2, more than 50% higher than all the other buildings on campus. Preliminary numbers suggest that post retrofit, ‘A’ Building is operating at a similar efficiency to the other existing buildings, at 20 ekWh/ft2.

Savings from energy cost avoidance are estimated to be $70,000 per year.