This session will discuss the advantages and challenges of using CO2 Heat Pumps for decarbonizing and efficiently electrifying commercial Domestic Hot Water systems. The session will outline and discuss the Mitsubishi Electric Heat2O DHW solution along with other CO2 DHW systems and their applications. The functionality, operation, scalability, and relevant design challenges related to these types of solutions will be explained. This session will discuss the use and benefit of CO2 as a refrigerant and its impact on environmentally sustainable buildings.

Dense packing cellulose in roof slopes has been a common insulation retrofit strategy in New England for a long time, however technically it has not been allowed by code without the inclusion of venting or foam insulation at the roof sheathing for condensation control. Previous BuildingEnergy presentations have suggested that further research should be done to evaluate whether vented attic space above unvented dense-packed slopes could manage moisture more effectively than insulating all the way up to the ridge.

Retrofitting buildings to reduce operating emissions is a key climate strategy. Viable, affordable, and scalable strategies must be implemented. However, we must avoid a surge of embodied carbon emissions from the manufacturing of building materials. This presentation showcases research and case studies evaluating the embodied carbon investment of varying retrofit assembly strategies and construction methodologies in cold climates with the expected operational carbon savings. We will hold an introductory how-to workshop on low embodied carbon approaches that exist today.

Think you know effective heat pump sizing and design? Significant market growth of cold-climate air-source heat pumps has resulted in new insights and lessons learned. Come explore new tools and best practices to enable improved design, sizing, and selection of ASHPs in this session with NEEP and Abode, and stay on the leading edge!

Many classroom environments are unhealthy and uncomfortable, creating poor learning environments with high absenteeism. Older, unventilated classrooms can be economically decarbonized with improved air quality and comfort. This session will present the conversion of a junior high school classroom, featuring a "rolling" room-by-room installation process using a community's local HVAC installation labor with one day of classroom downtime.

With rising determination to fight the climate crisis worldwide, practitioners are finding the Passive House standard a potent solution for the building sector. As passive and other sustainable building standards are proliferating worldwide, those standards meet a host of different location-specific challenges. This diverse panel of women architects and certified Passive House consultants are seeking to understand the adaptation of the Passive House standard globally.

The Massachusetts Maritime Academy consists of 16 buildings comprising approximately 600,000 sf, with heating for the buildings is provided by gas fired hot water boilers in each. They have undertaken a planning effort and initial design for a distributed campus-wide ground source heat pump system, combined with extensive energy retrofits. The plan consists of a neutral temperature Energy Transfer Loop that will tie various geo-exchange systems together to feed heat pump plants in each building.

Recent technology developments and incentive programs are creating new opportunities for ground-source heat pumps (GSHPs) at the building and neighborhood scale (networked geothermal). Practitioners designing and piloting GSHPs will describe how GSHPs can reduce the environmental burden on LMI communities by decarbonizing space and water heating.  Through design and case studies, they will describe what characteristics make a building or neighborhood a promising fit for GSHP implementation, and those posing significant challenges.

Electrification of HVAC systems and the elimination of fossil fuel heating in high rise building space conditioning systems poses unique design and system selection challenges.  Presenters will share two case studies for the design of VRF HVAC, one using air-to-air systems and one using air-to-water systems. They will discuss challenges including maximum piping lengths, acoustical restrictions, and airflow problems, and solutions including closely spaced condensers using CFD analysis and the design of access to piping and wiring in large condenser farms.

We will present tales from the trenches for ventilation approaches within the context of the Passive House building certification standard. This standard has set a high benchmark for low-energy buildings and is widely known as the most rigorous energy efficiency standard currently available. Attendees will learn how balanced ventilation is best applied in a cold climate at a large scale and how commissioning plays a key role in this process.