Originally built as a warehouse in 1943, the 11 Main Building in Portland, Oregon, was converted into an office space in 2014. Though its existing HVAC system was functional, its deficiencies created an uncomfortable indoor environment with occasionally poor indoor air quality. An energy engineering firm, Energy 350, occupies a large portion of the building’s main floor along with second story space that includes a mezzanine and two private offices—7,569 sq. ft. in total. Several months into the Covid-19 pandemic in summer 2020, Energy 350 management began to consider how they could provide the safest, healthiest and most comfortable indoor environment for employees who wanted to return to the office.

After considering a variety of HVAC system types, Energy 350 determined that a cutting-edge approach called very high efficiency dedicated outdoor air systems, or very high efficiency DOAS, would be the most advantageous upgrade. With very high efficiency DOAS, Energy 350 found a way to improve their building’s safety and comfort, while also helping reduce their overall energy use and carbon emissions.

Representing the next step in the ongoing evolution of HVAC design, this approach provides better temperature control and excellent indoor air quality for Energy 350’s employees, while reducing the building’s HVAC energy use by 84%, when compared to the pre-existing system.

With a variety of high-efficiency electric heating and cooling equipment options on the market, Energy 350’s engineers were afforded a great deal of flexibility when designing to their specific HVAC needs. And their high efficiency HRV improved the system’s efficiency so much that they were able to downsize their primary cooling system from 20 tons to 10 tons—while still maintaining comfortable conditions in even the hottest weather.

All in all, the Energy 350 team’s upgraded approach to HVAC design benefits their employees and building management by providing:

• Better indoor air quality due to filtered 100% outside air being brought into the space at a higher
  ventilation rate—without the increase in the energy usage typically incurred by systems with similar ventilation rates
• Increased occupant comfort from significantly better zonal temperature control and thermal stability
• Improved occupant productivity by improving indoor air quality and comfort
• Lower energy bills

Conversion Summary

Healthy air means safety and peace of mind.

Since the installation in early 2021, the building occupants have been very satisfied with the increased zonal control of temperature and the improved indoor air quality—and the data backs up their experience. CO2 and temperature data collected over 12 months demonstrate that the building’s thermal comfort and indoor air quality are excellent, and the equipment has been operating reliably and efficiently since installation.

The CO2 data shows that the office maintains levels consistently at or below 800 ppm, indicating that the new equipment is providing effective ventilation rates, and therefore may reduce harmful contaminant levels. The system’s avoidance of recirculated air helps to minimize the circulation and introduction of contaminated particles—an important way to minimize the spread of viruses like Covid-19 and other toxins inside the building. However, unlike competing high-ventilation HVAC systems, this approach does not increase energy costs despite providing 100% filtered outside air.

Energy 350’s employees were never more satisfied with the performance of the veryhigh efficiency DOAS approach than during an unprecedented heat wave when outside air temperatures reached 112 F. Despite the record-breaking temperatures, very high efficiency DOAS kept the office within 2 degrees of the 75 F temperature setpoint—even though the system’s cooling capacity had been reduced to 10 tons from 20 tons during the conversion. In addition to the cost savings and improved comfort, the project resulted in an 18 metric tons (59%) reduction in greenhouse gas emissions (GHG) annually4. Now almost one year after the conversion, the Energy 350 team remains very pleased with their HVAC system and confident that it will keep their building safe, healthy and comfortable.