When is HERS Verification Required?
compliance documentation indicates field-testing of specific energy efficiency
improvements for Title 24 compliance credit, an approved HERS (Home Energy
Rating Systems) certified rater must be used to conduct the field-testing. In California, these raters are part of CHEERS (California Home Energy Efficiency
HERS raters are considered special
inspectors by building departments.
provider and rater must be independent from the builder and/or subcontractor
installing the energy efficiency improvements to be tested and verified, and
can have no financial interest in the installation of the improvements.
Ducts – Duct Efficiency Improvements
that require HERS testing.
leakage testing –
credit if leakage verified to be less than 6% of fan flow.
Manual D duct design
– credit for the duct layout, engineering calculations and duct system
specifications included in the plans.
The HERS rater must either diagnostically test the system fan
flow and verify that the fan flow specified by the ACCA Manual D design is
achieved; or, remove the access panel and verify installation of the (TXV)
thermostatic expansion valve.
in conditioned space
– credit if less than 12 lineal feet of ducts outside the conditioned space.
surface area –
credit for maximum surface area of supply ducts in unconditioned space is 27%
(can only be used in conjunction with the ACCA Manual D duct design
(thermal expansion valve)
– used for split system central air conditioners to improve the performance and
efficiency of the air conditioner condenser.
Infiltration – Building Envelope Air Sealing
requires HERS testing using diagnostic blower door testing.
requires blower door testing to verify that the target leakage has been
achieved. The compliance author using
computer “performance” compliance chooses “SLA” for the Housewrap/Air
Infiltration credit, and the computer program specifies target CFM at 50
Verification Not Required:
Duct Efficiency Improvements and Building Envelope Air Sealing that do not require HERS testing, only building department inspection:
compliance credit available for ducts with insulation greater than R-4.2.
installation of a radiant barrier in the attic increases the duct efficiency by
lowering attic summer temperatures.
located in crawlspace
– credit is available for ducts installed in crawlspaces instead of attics with
all of the supply registers located in the floor.
house wrap –
credit can be taken for installation of an air-retarding wrap (insulative sheathing
and building paper do not qualify as air retarding wraps).
Housing. The standard design for multi-family
housing assumes tight ducts. Credit can
be taken for increased duct insulation and sealed ducts only.
Homes. At the builder’s option, HERS testing shall
be completed either for each house or for a sample of houses of the same
model. In order to take credit using
the sample of houses:
rater must diagnostically test and field verify the first house of each model.
considered the same model, houses shall be in the same subdivision and have the
same energy designs and features, including the same floor area and volume.
the initial testing is complete, the builder must identify a group of houses
from which a sample will be selected for testing. The group of houses must include those houses expected to be
ready for diagnostic testing within a 180-day period.
rater must select a minimum of one out of every seven sequentially
completed houses in the group. The HERS
rater must diagnostically test and field verify the houses selected.
failure is encountered during the sample testing, the HERS rater must
conduct re-sampling to assess whether the failure is unique or the rest of the
houses are likely to have similar failings.
re-sampling reveals a failure, the builder shall: 1) take corrective actions as
required in all unoccupied houses in the group and in occupied houses in the
group where homeowners have accepted field verification, testing and corrective
action; and 2) offer at no charge to homeowners of occupied houses in the group
to complete field verification, testing and corrective action if necessary.