SM 1.0—Introduction
All incentivize-qualifying building shell improvements in small multifamily properties shall follow general Existing Homes weatherization specifications unless otherwise noted in this section.
SM 1.1—Definition of Small Multifamily Property
For Energy Trust purposes, a small multifamily property is defined as a property with 2 – 4 units per structure in the predominant building type on the property. See Program Information sheet PI 320U for a complete list of available incentives.
The Small Multifamily programs and incentives are intended for apartments, condominiums, and townhouses but can also expand to include the variety of rental- and commonly-owned properties. For example, Small Multifamily may address several duplexes, triplexes or quadplexes on one property, or side-by-side townhomes with shared attics.
SM 1.2—Waivers for Unusual Conditions
When unusual conditions exist, Existing Homes may waive certain provisions of the weatherization specifications, or may substitute a different standard or method. The purpose of the waiver is to identify unusual conditions before work begins. Such waivers require pre-approval by Existing Homes. Please contact the Existing Homes program at existinghomesta@energytrust.org or call 1.866.365.3526 option 9.
SM 1.3—Carbon Monoxide Detectors
A functioning UL-listed carbon monoxide detector shall be installed in each unit, according to manufacturer’s specifications whenever a weatherization measure is implemented and a combustion appliance is present in a small multifamily structure, garage or attached space.
SM 1.4—Incentive Eligibility of Measures
Not all methods of measure implementation described in the section will qualify for an incentive from Existing Homes. Refer to Energy Trust’s Small Multifamily web pages for incentive details.
MF 1.5—Side-by-Side Structures (no horizontally overlapping living spaces)
The units in these structures shall be treated as separate, independent structures for the purposes of weatherization measures with no distinctions being made based on physical separation of attics and crawlspaces/basements or ownership status.
Illustration SM 1.5
Insulation
When no physical separation exists between individual attics or crawlspaces and basements, Existing Homes recommends all of the units be treated simultaneously. Attics and crawlspaces and basements of individual units in side-by-side structures may be treated as separate spaces for the purposes of weatherization improvements, regardless of physical separation between the individual areas. However, entire open attic or crawlspaces must meet required passive ventilation levels and applicable ground cover requirements. Refer to the Attic Insulation and Underfloor Insulation sections for relevant specifications.
Air Sealing
Blower Door testing and air sealing for all side-by-side structures shall treat each unit as a separate entity, regardless of barriers between the individual attics and crawlspaces. Adjacent units do not require depressurization as part of the Blower Door test when only one unit is being addressed at a time. Please refer to Air Sealing and Mechanical Ventilation sections for relevant specifications.
- Note for Home Performance with ENERGY STAR contractors:
BPI-tested unit tightness (CFM50) may not be reduced below 100 percent of Building Airflow Standard (BAS).
SM 1.6—Stacked Unit Structures with Separate Exterior Entrances
Insulation
Insulation and window installations for all stacked-unit structures shall treat the entire building shell rather than individual units. Refer to the Attic Insulation and Underfloor Insulation sections for relevant specifications.
Air Sealing
Fresh-air mechanical ventilation rated for continuous use and programmed to provide the full Minimum Ventilation Level, or MVL, is required for each unit in stacked small-multifamily structures if an incentive-qualifying air sealing measure is implemented. With installed mechanical ventilation, there is no limit to how tight a structure or individual unit may be air sealed. Blower Door testing and air sealing shall simultaneously treat the entire building shell with a Blower Door in a single exterior entrance for each unit of this structure type. Please refer to the Mechanical Ventilation section (MV 1.2) and the Air Sealing section for relevant specifications.
SM 1.7—Structures with one exterior entrance
Includes stacked structures with separate interior unit entrances off of one common exterior entryway. This building type includes stacked Single-family structures which have been converted to small-multifamily structures with a common entryway.
Insulation
Insulation and window installations for all structures with one exterior entrance shall treat the entire building shell rather than individual units. Refer to the Attic Insulation and Underfloor Insulation sections for relevant specifications.
Air Sealing
Fresh-air mechanical ventilation rated for continuous use and programmed to provide the full Minimum Ventilation Level, or MVL, is required in each unit in structures with one exterior entrance if an incentive-qualifying air sealing measure is implemented. With installed mechanical ventilation, there is no limit to how tight a structure or individual unit may be air sealed. Blower Door testing and air sealing shall treat the entire building. Please refer to the Mechanical Ventilation (MV 1.2) and the Air Sealing sections for relevant specifications.