As the HVAC industry moves toward electrification and higher efficiency standards, the combination of Dedicated Outdoor Air Systems (DOAS) with air-source heat pumps (ASHPs) is quickly becoming the gold standard in commercial building design. This integration isn’t just a trend—it’s a powerful solution for engineers and contractors aiming to deliver performance, sustainability, and comfort.
What Is a DOAS Heat Pump and Why Does It Matter?
A DOAS system is designed to deliver 100% fresh, outdoor air to a building—separately from the system that controls heating and cooling. This separation gives engineers more control over humidity, ventilation rates, and indoor air quality (IAQ). In buildings where occupant comfort and health are top priorities, DOAS is a smart move.
Key Benefits of DOAS:
- Consistent and code-compliant ventilation
- Independent control over latent and sensible loads
- Improved indoor air quality (IAQ) and comfort
- Flexibility for complex zoning and occupancy schedules
Why Air-Source Heat Pumps Are the Perfect Match
Pairing a DOAS heat pump with an air-source heat pump (ASHP) system allows for full electrification of the building’s HVAC operation. ASHPs provide both heating and cooling, reduce reliance on fossil fuels, and function well in most climate zones with proper design.
What Makes ASHPs Ideal for DOAS Systems:
- Efficient year-round performance
- Compatibility with energy recovery ventilation
- Simplified maintenance compared to boilers and chillers
- Scalable options for retrofits and new construction
Best Practices for DOAS + ASHP Design
1. Calculate Loads Separately
Ventilation (latent) and space conditioning (sensible) should be addressed independently. This allows for right-sizing of equipment and better humidity control.
2. Incorporate Energy Recovery
Use energy recovery wheels or enthalpy cores to capture heating or cooling from exhaust air. This reduces the load on the ASHP and improves system efficiency.
3. Size for Outdoor Conditions
Design heat pumps with cold-climate performance in mind. Use variable speed compressors and coil defrost strategies to maintain capacity.
4. Maintain Control Separation
Integrate building management systems (BMS) that treat ventilation and conditioning as independent zones to optimize setpoints, timing, and response.
Applications and Market Impact
Whether you’re designing a school, office, or multifamily project, DOAS + ASHP solutions are cost-effective over time, offer strong ROI on energy savings, and reduce a building’s carbon footprint.
Government incentives, decarbonization policies, and stricter energy codes are making these systems more attractive than ever.
Final Thoughts
If you’re an HVAC contractor, mechanical engineer, or design-build firm, understanding how to design DOAS systems with air-source heat pumps isn’t just a good idea—it’s a competitive edge. As demand for high-performance, fully electric HVAC systems grows, this integration will define the next generation of smart buildings.
