Low-GWP Mechanical Modules for Rapid Deployment Project (LG-MM)

Project Update

This project was completed in 2024. This project approach studied, field demonstrated and evaluated different types of low-GWP combined mechanical systems in four units across two affordable multifamily properties in two different climate zones.

High-level findings of this project include:
1. Form factor—shape, size, and packaging product—and system component layout are two of the strongest determinants of whether a combined mechanical system will work in a multifamily retrofit application, and combined mechanical systems come in a variety of form factors.

2. Benefits associated with the heat recovery capabilities that are often a key selling point for some combined mechanical systems can only be realized during periods of coincident space cooling and hot water demand. There is a low occurrence of coincident demand periods in many residential applications. There are potential ways to improve the heat recovery capabilities of these systems, which are described in the Conclusion below.

3. Combined mechanical system products developed with specific retrofit applications are most primed for market development and most likely to be successful retrofit solutions; however, there are very few of them available right now. The Villara AQTA is an example of a product designed for a specific application. It slots in easily in the typology for which it was designed, but would not be a good retrofit solution

4. Combined mechanical systems that integrate ventilation are likely to encounter challenges with code compliance due to exhaust re-entrainment. Experiences from this project indicate that current relevant codes are unclear and approaches to code compliance are burdensome. The research team’s measurements support exception 4 of ASHRAE 62.2, Section 6.8 that it is reasonable not to have 10ft of separation between intake and extract airways.