The chief consumer of building energy is the HVAC system. In fact, it’s responsible for about 40 percent of the total energy used, with lighting coming in a distant second at 25 percent. Out of this HVAC energy, the number one contributor is the powering of fans for ventilation at 34 percent. Therefore, to realize high-performance green buildings, the place to start is improving HVAC – centering on ventilation/efficiency.
RenewAire’s Energy Recovery Ventilators (ERVs) and Dedicated Outdoor Air Systems (DOAS) boost HVAC efficiency by reducing ventilation energy use. This is achieved by reusing otherwise-wasted total energy (heat and humidity) from the exhaust airstream to precondition fresh and filtered outdoor air coming inside.
The results of this process are enhanced IAQ, decreased energy consumption, downsized equipment, and HVAC ventilation loads cut by up to 70 percent. ASHRAE recognizes the crucial role ERVs and DOAS play in improving both the human condition and the bottom line, as well as protecting the environment. Therefore, the systems are required in several standards and most rigorously in 189.1.
In that light, Standard 189.1 incorporates all of 90.1’s energy recovery requirements and then some. Both 189.1 and 90.1 require ERVs in several instances based on climate zone and percent of outdoor air at full design airflow rate, and with each new update, more ERV requirements are added. For example, in 2016, 90.1 – and hence 189.1 as well – raised the minimum exhaust air energy recovery threshold.
Where 189.1 goes even further than 90.1 is in energy recovery effectiveness. Currently, 90.1 requires ERVs to have at least 50 percent energy recovery effectiveness. In 189.1, the energy recovery system has to have a minimum of 60 percent energy recovery effectiveness.
Since ERVs and DOAS create cleaner and healthier indoor air while optimizing energy efficiency, they also play key roles in the most stringent green-building standards and certifications. For example, they’re required by LEED, Green Globes, ENERGY STAR, Net Zero, Passive House, PHIUS, Living Building Challenge, HVI, AHRI, and WELL Building Standard, to name a few.
Why DOAS is Critical for Standard 189.1
Commercial buildings require outside air whenever a space is occupied to meet ventilation standards and maintain IAQ. Incoming ventilation and make-up air typically account for more than 80 percent of a building’s dehumidification load. Hence, decoupling outdoor-air demand and interior-load demand allows each system to operate independently to achieve optimized operational efficiency.
A revolutionary idea proposed two decades ago was to handle the outdoor air (OA) and return air separately in building HVAC systems. This new concept describes the application of DOAS for delivering dehumidified air to buildings to improve IAQ and thermal comfort. Research concluded that DOAS provided many potential advantages compared to conventional HVAC systems.
Due to DOAS’ unique ability to enhance IAQ while reducing energy use, the units are required in ASHRAE’s building standards, such as 189.1. Utilizing a DOAS ensures compliance with proper multiple space ventilation and adequate IAQ. And specific codes do call for DOAS-type products to deliver 100 percent outdoor air. In addition, DOAS with energy recovery is a mandated feature for most U.S. code jurisdictions.
Benefits of Implementing ERVs, DOAS, and Standard 189.1
A high-performance green building sounds impressive, but what does it really mean and, most importantly, what are the benefits? Essentially, by adhering to the high standards of 189.1 – and implementing ERVs and DOAS – the result is a building that supports the three pillars of sustainability: people, planet,, and profit.
Here’s how this is possible: 1) With enhanced IAQ, indoor occupants’ health, cognitive function, productivity, and well-being are strengthened, 2) reducing the amount of energy buildings use when ventilating backs sustainability efforts and protects the environment, 3) optimizing energy efficiency reduces HVAC loads and downsizes equipment, which can cut ventilation energy costs by up to 65 percent.
Green Buildings and the Future
ASHRAE is constantly seeking to guide the industry with the latest in green-building best practices, and Standard 189.1 is at the peak of those efforts. To make this rigorous green-building standard possible, energy recovery ventilation technologies, such as ERVs and DOAS, are at its core and required in many building applications.
Therefore, by following the prescriptions of Standard 189.1, and implementing ERVs and DOAS, the results will be the highest-performance and greenest buildings on the market today. And, going forward, you should be on the lookout for a growing number of ERV and DOAS code requirements since the systems are so effective at enhancing IAQ and saving energy.