How to Integrate HVAC Load Reduction® with Dedicated Outside Air Systems (DOAS), Energy Recovery Ventilation (ERV), and Variable Refrigerant Flow (VRF) Units

Published 08/19/2021
By Alex Goodwin
enVerid HLR Install - Financial Services HQ NYC

enVerid HLR units installed in lower Manhattan, NYThe use of Dedicated Outside Air Systems (DOAS) and Energy Recovery Ventilation (ERV) is growing quickly, driven by the adoption of Variable Refrigerant Flow (VRF) units, Fan Coils, and other de-centralized HVAC systems. enVerid’s HLR Modules easily integrate with both DOAS and ERVs, offering significant savings on system and operational costs. The HLR Modules complement de-centralized HVAC systems: by cleaning the indoor air, the HLR reduces the load on the DOAS by 60 to 80% enabling the use of a much smaller DOAS. Also, since general exhaust is reduced along with outside air, ERVs can be downsized or eliminated in some cases, resulting in smaller, more efficient systems that require less space and are less expensive to operate.

HLR modules can integrate with DOAS/ERV in many ways. The scenarios illustrated below are the most common and can be used in ducted or plenum installations, with or without ERVs.

Scenario 1: Integrating with Air Handling Units (AHU)

HLR-DOAS-AHU integration

In this scenario, the AHU supplies a mix of Outside Air (OA) from the DOAS and Return Air to the building. The HLR module cleans a side stream of the return air and reduces the need to bring in OA to control indoor pollutants.

enVerid’s real estate case study details this scenario and shows a 65% OA reduction in a 50-story skyscraper.

Scenario 2: DOAS serving a VRF system

HLR - DOAS - VRF integration
*Adding return air to the DOAS creates a mixed-air system

In systems using a DOAS coupled with remote VRF units, HLR modules pull return air from an adjacent ceiling plenum and clean the return air before it is recirculated throughout the system. This decreases the volume of outside air required by the AHU for ventilation. The approach may also be used with chilled beams, fan coils, heat pumps, and other terminal equipment.

This LEED Gold case study further illustrates this configuration and resulting DOAS downsizing and energy savings.

Scenario 3: Decoupled DOAS and HLR SystemsHLR - DOAS decoupled

In some systems serving large, open spaces like warehouses, HLR 100M modules can be installed separately from the DOAS to clean the air locally within the space. The DOAS can be downsized, saving mechanical floor space, and the independence of the two systems reduces duct runs.

Our team is happy to provide technical assistance designing HVAC systems using HVAC Load Reduction® modules: email us.


Alex Goodwin

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