Tackling ventilation and air conditioning can involve a few different measures. The most common upgrade for ventilation systems is variable speed drives. These drives fine-tune the fresh air supply based on either a schedule or air quality monitoring. There’s also the option to use heat recovery ventilation, transferring heat from stale exhaust to incoming fresh air to substantially reduce energy use. High-efficiency chillers can dramatically reduce electricity use for cooling. Many buildings can actually benefit from free cooling systems that use cool outdoor air at night, or during spring and fall, to supplement traditional cooling systems.