The Foundation of SWACH
The CEC’s Public Interest Energy Research program funded three important LBNL studies conducted by SVACH’s principal investigators. Those three studies provide key background for the SVACH project.
- The Residential Energy Savings from Air-tightness and Ventilation Excellence (RESAVE) project reported on analysis of measured air-tightness of homes in California. RESAVE also developed advanced methods for analyzing energy and IAQ impacts of air-tightness and ventilation.
- The Efficiency Characteristics and Opportunities for new California Homes (ECO) study (CEC-500-2012-062) examined the as-built energy-related features and performance of homes constructed to meet 2008 Title 24 standards.
- The data gathering project Healthy Efficient New Gas Homes (PIR-14-007) looked at the IAQ of post-2008 new housing. Together, these studies are the primary reference for energy and IAQ modeling for newer California homes.
SVACH Phase 1
Phase I rests on ASHRAE Standard 62.2-2016 assumptions in which equivalent dose is limited to a generic contaminant. The concept of a generic contaminant is a way of saying “any and all contaminants.” Therefore we consider only ventilation and occupancy and not air cleaning and measurement of specific contaminants. We’ll finish Phase I in time to include approved SVACH content in the 2019 version of Title 24.
Smart Ventilation Concepts
The principal concepts of smart ventilation are these.
- Sensing operation of other fans,
- Time-shifting to less-energy-intensive periods,
- Evaluating health impacts only during occupied times
LBNL will explore these smart ventilation concepts through simulation and will use the simulations to develop control algorithms and determine acceptability of control strategies. These algorithms and control strategies could be incorporated into California building energy codes and ASHRAE 62.2.
Phase I will also begin to look at multi-zone impacts. ASHRAE 62.2 and current California assumptions is that each dwelling is a single, well-mixed zone. This assumption is different from that taken for homes in most other developed countries. The Canadian ventilation standard has room-by-room requirements. We expect that ZNE and other advanced dwellings — including new, existing, and multi-family — will have very tight envelopes. They will have small HVAC systems that may not mix home air as much as the current central forced-air systems.
Trends towards mini-splits in high-performance homes lead to zonal solutions for heating and cooling. Compared to conventional homes, the tighter envelopes used in ZNE homes result in lower natural infiltration. Tighter envelopes also reduce natural infiltration-driven or temperature-driven air movement among rooms. All of these factors will lead to more zonal heating, cooling, and ventilation systems. LBNL will explore this issue through multi-zone simulation using CONTAM software to determine whether zonal ventilation requirements are appropriate for Title 24. If so, LBNL will suggest what these zonal requirements might be.
Aereco, a European ventilation manufacturer, is interested in developing a zonal ventilation product for the California market. Aereco will be a cost-sharing partner, providing cash to the project and sharing expertise and simulation capabilities with the SVACH team.
SVACH Phase 2
Phase II will go beyond the Phase I concept of a generic contaminant to the idea of quantifying and controlling a combination of COCs. The expectation is that this contaminant quantification and control will improve IAQ while reducing energy costs. This technological advance is the first major step toward improved alignment of ventilation requirements with health-based data. This improved alignment can support building codes and standards. This approach includes identifying, sensing, and controlling ventilation based on COC concentrations (for example: particles and formaldehyde).
IAQ Metrics and Simulation
A key factor in contaminant control is developing an IAQ performance metric that quantifies a contaminant’s health impact. This effort will begin with an interim report in Phase I, and drive the technological potential of Phase II. U.S. DOE supports IAQ valuation approaches and has agreed to co-fund this effort. Existence of health-impact metrics will stimulate industry to develop effective sensors and controls for residential ventilation systems.
Phase II simulations will be similar to those we performed in Phase I but will use the new Phase I metrics. The new IAQ metrics will advance ventilation technology from the current relative-dose metric of ASHRAE 62.2. LBNL will simulate air cleaning and filtration in addition to the simpler assumptions used in Phase I. Results of this project will support Standard 62.2’s continuous maintenance process to so California can reference a consensus industry standard. The SVACH team are members of and consultants to the ASHRAE 62.2 committee, which will help ensure transfer of research results from SVACH to the ASHRAE standard.
Some of the approaches developed for contaminant control will be novel and will require some field testing. LBNL energy simulations will include both natural gas and electric space-conditioning loads. These simulations will be relevant for Title 24 and in addition to the ASHRAE 62.2 standard. Any gas analyses will be supported by cost-share partners. During Phase II, we will do limited testing in a facility or home to corroborate simulation results, however extensive field tests are beyond the scope of SVACH.
SVACH Coordination with Stakeholders
SVACH’s leadership will continue to coordinate with an Interagency Agreement that LBNL has had for several years with U.S. DOE, the U.S. Environmental Protection Agency (U.S. EPA) and the U.S. Housing and Urban Development agency (U.S. HUD). We’ll invite representatives from all three organizations to participate in the SVACH Technical Advisory Committee. U.S. DOE’s Building America Program will be the cost-share partner of this interagency agreement. The strategic plan and annual operating plan for the Building America program at U.S. DOE will support SVACH for its duration. The SVACH team communicates with the U.S. DOE Technology Development Manager, Eric Werling. And the team closely coordinates the Building America Program and the Healthy and Efficient Homes Program.
Lawrence Berkeley National Laboratory; Building Technology & Urban Systems Division; Original research and literature reviews on residential ventilation.