Lawrence Berkeley National Laboratory

Traditional control sequences for HVAC systems in large commercial buildings have historically led to poor energy efficiency. To overcome this issue, ASHRAE has recently published Guideline 36 (G36), a collection of high-performance control sequences aimed at reducing energy consumption and cost for building owners. While these sequences are effective in increasing energy efficiency, their influence on a building's capacity to deliver demand flexibility remains uncertain. Prior research suggests a potential trade-off between energy efficiency and demand flexibility because permanently reducing energy use negatively impacts the available amount of load that can be reduced when responding to grid signals. To investigate this hypothesis, we created Modelica simulation models for an air handling unit with a G36 trim-and-respond sequence, calibrated these models to a fully instrumented experimental building testbed X1A in FLEXLAB, and simulated different demand flexibility scenarios. Counter to expectations, results show that, during a “shed event” with prior pre-cooling, G36 reduces demand by around 3.1 W/m2 more than the traditional control sequences, at the cost of a reduction in comfort (1.5 °C-hour/day) across five different cities across the United States. Our results provide encouraging evidence that, under the tested conditions, G36 does not decrease demand flexibility. This study should increase the confidence of building owners, designers, and operators who are looking to take advantage of demand flexibility programs while complying with increasingly stringent building energy efficiency standards.