Item 6A - Energy Code memo1
MEMORANDUM
To: Landmarks Board
From: Maureen Rait, Executive Director of Public Works
David Driskell., Executive Director of Planning, Housing + Sustainability
Dave Thacker, Building Services Manager/Chief Building Official
Kendra Tupper, Energy Services Manager
Elizabeth Vasatka, Business Sustainability Coordinator
Date: October 5, 2016
Subject: Energy Codes: Update on the City’s Long-Term Strategy and Seeking Feedback
on the Proposed Near-Term Energy Code Amendments
EXECUTIVE SUMMARY
This memo outlines the long-term strategy for Boulder’s energy codes and proposed
amendments for the next building and energy code update (late 2016). Staff has provided an
outline of the long-term strategy (Attachment A) for context, and is updating and seeking
feedback from the Landmarks Board on the proposed near-term energy code amendments
(Attachment B).
Long-Term Strategy
The City of Boulder has set an aggressive goal of adopting net zero energy (NZE) codes by
2031, and has developed a strategy and pathway to achieve that target. Staff recognizes that in
order to support the city’s Climate Commitment and sustainability goals, energy codes must
begin to address sustainability beyond just energy use such as transportation, water, indoor
environmental quality and waste. In fact, when staff projected emissions reductions out to 2050,
savings from the implementation of progressively more stringent energy codes was the largest of
any building efficiency program, including EnergySmart, SmartRegs and the Building
Performance Program.
2
Proposed elements of the long-term strategy for energy codes include:
1. Pathways for achieving high performance NZE codes including: a phased schedule for
NZE deadlines, early adopter incentives, allowance of off-site renewables, future adoption
of outcome-based codes and the encouragement of all-electric buildings.
2. A six-year cycle for major updates linked to the national code adoption schedule, with
local evaluation and updates every three years.
3. The prioritization and phasing schedule of non-energy sustainability requirements for
commercial energy codes.
Proposed Near-Term Updates
Staff has developed proposed updates to the building and energy code, which is tentatively
scheduled to be presented to City Council for consideration and adoption in late 2016. The
proposed effective date of these changes is early 2017.
Proposed near-term building and energy code updates include:
1. Restructuring and updates of the residential energy code, Green Building and Green
Points (link to the current Green Building and Green Points program); and
2. New prescriptive requirements for commercial buildings, including only allowing this
prescriptive pathway for alterations and new construction/additions with a construction
cost less than $500,000.
3. Other miscellaneous updates including: revising how multi-family units are addressed
and allowing off-site renewable energy for energy code compliance.
Questions
1. Does the Board have feedback on the proposed near-term updates?
2. Does the Board have any questions on how the city’s adopted building and/or energy codes
address historically significant buildings?
BACKGROUND
Please refer to Attachment B for an overview of energy and green codes. This Attachment
provides background information on national energy and green codes, definitions of key terms
that are used throughout this memo and a brief history of Boulder’s energy codes.
Goals and Objectives of the City’s Energy Codes
The overall long-term goal for the city’s energy code is to build high-performance, NZE
residential and commercial buildings. The objectives below are designed to support this
overarching goal:
Supporting the Climate Commitment
To achieve and sustain significant greenhouse gas (GHG) reductions in support of the
city’s overall Climate Commitment
3
To reach NZE codes by 2031
To support technologies and practices that will move the community towards local,
distributed and renewable energy systems (for both buildings and transportation) that
support the goal of 100 percent renewable electricity, as well as economic vitality and
community resilience
Promoting High-Performance Buildings
To promote sustainable building practices throughout the lifecycle of the building
process (e.g., waste management, water management, transportation impacts, etc.)
To promote the development and ongoing maintenance of safe, comfortable and high
performing buildings
To support energy resilience (the ability to maintain operations during grid failure)
Creating Effective and Viable Codes
To adopt codes that are feasible to update regularly, implement and enforce
To provide building owners and design professionals with viable and economically
feasible paths to comply with energy codes that are straightforward and easy to
understand
What is Net Zero Energy (NZE)?
While NZE can be defined a number of ways, in this context, NZE means:
The amount of renewable energy produced on-site, plus the amount purchased from
approved community energy systems, is equal to or greater than the annual energy
consumption of the site.
This definition makes it possible for all buildings to become NZE even with poor solar access or
other site constraints.
ANALYSIS: NEAR-TERM CODE UPDATES
As the city evaluates and updates its energy codes every three years, staff has gathered
stakeholder feedback on some of the challenges related to compliance with current codes. Staff
has drafted updates based on the feedback received which will be presented to council for
adoption in late 2016 with an effective date in early 2017. Specifically, staff is proposing the
following near-term energy code amendments:
Restructuring and updates to the current residential energy code, Green Building and
Green Points (GBGP), including amendments to the International Residential Code (IRC)
to require electric vehicle charging infrastructure
New prescriptive requirements for commercial buildings, including amendments to the
International Building Code (IBC) to require solar photovoltaic (PV)-ready and electric
vehicle charging infrastructure for multi-family and commercial buildings
4
In addition, the city plans to improve the compliance process by streamlining steps and providing
more consistent and detailed guidance. Please see the July 19, 2016 Information Packet Memo
(Attachment G) for a summary of the scope and intended outcomes of this compliance
improvement effort. Staff also plans to make a few administrative updates to clarify the common
points of confusion, such as how to consistently measure square footage in gaining compliance
with the Green Points program.
Near-Term Residential Energy Code Updates
Planned amendments to the current residential building and energy code are as follows:
1) Eliminate the point structure in the Green Building and Green Points program, and
prioritize and update key measures as mandatory (see Table 1).
2) Implement a sliding Energy Rating Index (ERI) scale based on floor area which will
require residential buildings larger than 5,000 square feet (sf) to be NZE (see
Figure 1).
3) Revise the ERI requirements for additions to impose more efficient requirements for
larger homes and additions. ERI requirements for additions will only apply if the
addition is 1,000 sf or larger – smaller additions will be required to meet the prescriptive
requirements of the 2012 International Energy Conservation Code (IECC).
4) Revise alterations requirements as follows:
a) Eliminate the Green Points program “point” options and the 500 sf threshold, to
provide clarity and streamline the building permit process.
b) Change the trigger for alteration requirements from measured floor area to the
percentage of the project cost1 compared to the assessed or appraised value of the
existing structure (see Table 2).
c) Mandatory efficiency measures will be required for all alterations; these include:
energy advising, energy audits and new construction regulations (see Table 2).
1 Project cost will be either the customer’s construction cost or the city’s project cost evaluation,
whichever is higher.
5
Table 1: Proposed Changes to the Point Structure of GBGP
Requirements Current
Requirements
Proposed
Requirements
Energy Performance1 ERI/HERs ERI/HERs
Waste Management2 Mandatory Mandatory
Preservation of Natural Resources: Require shading from existing
and new trees; organic, low water landscaping practices; and
stormwater management3 Optional point Mandatory
Solar Photovoltaic “Ready:” Pre-wire for solar PV and a space
allocation roof plan Optional point Mandatory
Electric Vehicle Charging Infrastructure: Require the installation of
both 120-Volt and 240-Volt charging outlets in any dedicated off-street
parking space for single family homes and townhomes. For multi-
family units, require charging infrastructure (120 and 240 V outlets) for
7.5% of the parking spaces, and require Level 2 dual port charging
stations for 2.5% of the spaces.5
NA Mandatory
(NEW)
Water Efficiency: High efficiency kitchen and bathroom fixtures Optional point Covered in
IRC4
Sustainable Products: Require the use of re-used, recycled, bio-based,
environmentally certified or locally sourced materials Optional point Not required
Solar Thermal “Ready”: Require solar thermal systems to heat hot
water (water heating, space heating and/or pools and spas) Optional point Not required
Material Efficient Framing: Require efficient use of lumber and
methods to frame a house and design the structure Optional point
Not required6 Indoor Air Quality: Require means of detecting, reducing and
mitigating indoor air pollutants Optional point
Design Process and Education: Require green building design
professionals and an owner manual for efficient operation Optional point
1 Updated for both new construction (Figure 1) and additions.
2 These requirements may be revised to increase the diversion rates (based on the current recycling
markets).
3 A landscaping plan is required for new construction must be submittal with the permit. A landscape
rehabilitation plan will be required for additions and alterations.
4 Staff will increase the current requirements in the International Residential Code (IRC) to match the
current national EPA’s WaterSense Standards
5 This requirement is only triggered when there are at least 25 parking spaces.
6 An updated HERS rating software will be released in the 2017, which will incorporate these sustainability
attributes. The design manual will remain a requirement.
6
Figure 1: Proposed Changes to Efficiency Requirements for New Homes
Table 2: Alterations Requirements
Thresholds for
requirements
Project cost is
≤20% of assessed
value of existing
property
Project cost is 21‐50% of
assessed value of existing
property
Project cost is >51% of
assessed value of existing
property
Measures
All energy and building code requirements (for the scope of the alteration)
EnergySmart
Advising1
EnergySmart Audit2 and
Advising Triggers new
construction
requirements
Air sealing and insulation
in ceiling and walls3
Crawl space conditioning3
0
10
20
30
40
50
60
0 1000 2000 3000 4000 5000Energy Rating Index (ERI)Residential Structure Floor Area (square feet)
Current2019
2022
2017
2025
2028
2031
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1 Homeowner must contact EnergySmart and discuss the construction project with an energy advisor
to ensure efficiency opportunities are maximized.
2 Homeowner must enroll in EnergySmart and receive an energy audit that includes a blower door
test that measures infiltration of the existing building.
3 When applicable, implement these measures to code standards.
Near-Term Commercial Energy Code Updates
Revisions to the prescriptive path of Boulder’s commercial energy code are being proposed with
the primary goal of improving usability and compliance while maintaining or increasing energy
efficiency. While the performance pathway for new construction and major alterations must
have an energy performance which is 30 percent better than IECC 2012, the prescriptive path is
limited by market availability and construction and cost feasibility per individual requirement.
The changes are described below, along with rationale for the changes.
Table 3: Proposed Changes to Commercial Energy Code
Proposed Change Rationale
When the Performance (Modeling)
Approach is Required or Allowed:
For new buildings, additions, and major
alterations (more than 50 percent of the exterior
wall area is being demolished) with a project
cost greater than or equal to $500,0002,
compliance using the modeling based
performance approach will be required.
Compliance using the prescriptive approach for
these projects will no longer be allowed.
Alterations which are not considered “major
alterations” are required to comply using the
prescriptive approach.
Performance approach compliance is designed
for new construction and major alterations that
must achieve the city’s energy requirement of
30 percent better than IECC 2012. This
requirement is so efficient that it requires the
whole building tradeoffs allowed via the
performance pathway.
For smaller scope alterations, the prescriptive
pathway is much better suited.
2 A threshold of a project cost of $500,000 was chosen as the limit for allowing the prescriptive path for new
construction and additions based on the typical costs of energy modeling require for the performance and
outcome based paths. This limit should keep the modeling costs to below 2.5 percent of the total project cost.
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Proposed Change Rationale
Revision of Prescriptive Requirements:
The custom prescriptive pathway is being
replaced with amendments to the IECC 2012
prescriptive path. These amendments will
increase the stringency of IECC 2012
requirements up to what is allowed by federal
regulations, or what is being proposed for the
2018 version of the International Green
Conservation Code (IgCC). These changes
address insulation levels, fenestration
performance, lighting power and equipment
efficiency.
Current prescriptive requirements in the
commercial energy code are extremely
stringent, without the tradeoffs allowed
through the modeling-based performance
path. Overwhelming stakeholder feedback
indicates that the requirements are confusing
and extremely difficult, if not impossible, to
achieve.
These new prescriptive requirements will
replace a complicated set of custom
requirements. Simplification of prescriptive
requirements that are based on nationally
developed standards will improve compliance
and simplify enforcement.
Operable Window/Door Shut Off:
New mandatory requirement for operable
windows and doors to have switches which will
shut off heating and cooling equipment when
doors or windows are left open.
This change prevents wasted operation of
heating and cooling equipment when doors or
windows remain opened. These requirements
are based on requirements already present in
other energy codes.
Removal of the Building Area Method:
For determining prescriptive interior lighting
power, the Space by Space Method is now the
only allowed approach.
The Space by Space Method is based on the
details of the proposed design. The Building
Area Method is an approximation based on
“typical” space allocations for a building type.
Appliance Requirements:
New mandatory requirement that appliances
installed in multi-family buildings be
EnergyStar rated.
Requiring EnergyStar appliances in new
residential occupancies will ensure that this end
use is addressed even when multi-family
buildings are covered under the commercial
energy code.
Solar “Ready” Requirements:
Mandatory requirement to identify roof
locations for installation of future solar systems
, and keep these areas clear of obstructions.
Locations for conduit and other electrical
equipment that would be required for the solar
system must also be identified. This equipment
need not be installed.
Identification and reservation of space for future
solar systems will greatly facilitate future
installation of solar systems where solar
systems are not currently required or where
larger systems may be required in the future.
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Proposed Change Rationale
Requirements for Electric Vehicle (EV)
Charging Infrastructure:
The following will be required for offices,
industrial buildings and multi-family buildings3:
7.5% of parking spaces must have (1) 240-V
and (1) 120-V charging outlet
2.5% of parking spaces must have a Level 2,
dual port charging station installed
Lodging facilities will be required to install
charging stations (Level 2, dual port) for 1% of
parking spots (a minimum of 1).
Workplace EV charging provides employees
that live in multi-family units without EV
charging the opportunity to drive an EV. There
is also a need for EV charging facilities at
lodging facilities, as more and more rental car
agencies are beginning to offer EV options.
However, there has been very little usage in
general public charging stations provided at
commercial buildings for transient visitors.
3 There must be at least 25 parking spaces to trigger these requirements.
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Other Miscellaneous Energy Code Updates
Table 4: Summary of Other Miscellaneous Energy Code Updates Impacting Both Residential
and Commercial Buildings
Topic Description of Update
Multi-family
Units
1) Townhomes and duplexes will be covered under residential energy code. If there
are any shared commercial spaces, they must comply with the prescriptive
requirements for the commercial energy code.
2) All other multi-family buildings are covered under the commercial energy code,
regardless of the number of stories.
Water Fixture
Use Rates
The water fixture use requirements covered under the International Plumbing Code
(IPC) and the International Residential Code (IRC) will be amended to be as
efficient as current national WaterSense standards put out by the Environmental
Protection Agency (EPA).
Allow Off-Site
Renewables
Due to shading, roof space constraints and high energy intensity buildings (such as a
data center or lab), off-site renewable energy will be required for some residential
and commercial buildings to achieve NZE. Off-site renewable options will only be
allowed if all on-site renewable options have been exhausted.
Community solar gardens, but not Renewable Energy Credits (RECS), will be
allowed to meet required overall energy performance for new buildings and major
alterations.
NEXT STEPS
In terms of the next code updates, there are several more steps in the coming months. The
tentative schedule is as follows:
November 3, 2016: Planning Board will review near-term energy code amendments.
November 15, 2016: City Council First Reading of proposed energy code amendments.
December 6, 2016: City Council Second Reading of proposed energy code amendments.
Q1 2017: Amendments to energy code become effective (following 60-day grace period
after adoption)
Q1 2017: Noresco, the city’s consultant for this work, will conduct staff training and
develop supporting documentation and resources on the city’s website to help explain
the energy codes
Q2 2017: Staff will implement changes to improve energy code compliance
Once the 2018 version of the national codes are released, the city will work quickly to adopt the
2018 versions of the codes, with local amendments.
Q1 2018: Staff will review the newly released 2018 codes, including IECC 2018 and
IgCC 2018
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Q3 2018: Staff will review the next building code update with the relevant boards,
including moving from IECC 2012 to IECC 2018 and beginning to adopt portions of
IgCC 2018
Q4 2018: Planned adoption of full set of ICC 2018 building codes, with amendments
Q1 2019: New building codes (based on ICC 2018 codes) becomes effective
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ATTACHMENT A: LONG-TERM STRATEGY
Proposed elements of the long-term strategy for energy codes include:
1. The long-term pathway for achieving high performance, NZE codes including:
a. The allowance of off-site renewables to meet energy code requirements.
b. The adoption of an outcome-based pathway for commercial energy codes.
c. A schedule for when new buildings would need to meet a NZE code.
d. Early adopter incentives for designing NZE buildings before the requirements ARE
phased in.
e. The encouragement of all-electric buildings.
2. A six-year cycle for major updates linked to the national code adoption schedule, with
local evaluation and updates every three years (see the July 19, 2016 Information Packet
Memo for more information).
3. Prioritization and a proposed phasing schedule of adopting IgCC’s non-energy
sustainability requirements for commercial codes, and subsequently amending other
portions of the city’s codes that may currently address these issues (see the July 19, 2016
Information Packet Memo for more information).
The City of Boulder has set an aggressive goal of having NZE codes in effect by 2031, and this
recent work effort represents staff’s first attempt at charting a clear strategy and pathway to
achieve that target. The figure and table below provide more details on the key components of
the long-term strategy and illustrate when each is suggested to go into effect.
Figure 2: Long‐Term Strategy Key Component Timeline
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Table 5: Long-Term Strategy Key Components (Post 2016/2017 Updates)
Key
Component of
Long-Term
Strategy
Description Scope Phasing
Off-Site
Renewables
Due to shading, roof space constraints and high energy
intensity buildings (such as a data center or lab), off-
site renewable energy will be required for many
buildings to achieve NZE. Off-site renewable options
will only be allowed if all on-site renewable options
have been exhausted.
Community solar gardens, but not Renewable Energy
Credits (RECS), will be allowed to meet required
overall zEPI scores for new buildings and major
renovations.
Commercial
and
Residential
2017
Require a Base
Level of
Efficiency
Prior to
Renewables
The following method will ensure that building
efficiency is prioritized before the use of renewables:
A zEPI score (commercial) or ERI (residential) is
required for overall compliance.
A zEPI score of 45 or an ERI of 50 must be
achieved through efficiency alone; renewables can
then be used to achieve the code specified energy
target (currently zEPI 38 for commercial and ERI
value of 25 to 60 for residential).
Commercial
and
Residential
2019
Outcome-Based
Codes for
Commercial
Buildings
Staff plans to pilot a voluntary outcome-based energy
code for new commercial buildings, which will be
based on the actual, measured energy consumption of
the building post-occupancy.
Outcome-based codes bring energy behavior of
occupants, maintenance and operating practices
under the purview of the codes. These factors can
account for 50 percent of a building’s energy use.
This is a new approach to energy codes; compliance
and enforcement approaches are still under
development nationally.
Data collected from the Building Performance
Program will aid this process.
Commercial
Voluntary
pilot 2019;
possibly
mandatory
in 2022
(depending
on pilot
outcome)
Schedule for
NZE
Compliance
Staff is planning a slightly accelerated schedule for
NZE for new residential and commercial buildings.
Those with low energy use intensity and high roof to
floor area ratios, can reasonably be required to be NZE
sooner than 2031. This allows NZE requirements to be
phased in over time to minimize enforcement issues,
and accelerates achievement of the city’s Climate
Commitment goals.
Commercial
and
Residential
2019 to
2031
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Key
Component of
Long-Term
Strategy
Description Scope Phasing
Early Adopter
Incentives
Providing incentives for buildings to be NZE before
it is required by code encourages owners and design
teams to develop advanced designs and share
feasible examples for other buildings.
These incentives might include reduced city fees,
expedited plans approvals and/or positive publicity.
Commercial
and
Residential
2020
Encouragement
of All-Electric
Buildings
To support long-term goals, local code amendments
should begin encouraging all-electric buildings within
the next five years.
Many of the city’s long-term goals will eventually
require that the use of natural gas in buildings be
minimized or eliminated: the goals of having all
new buildings be NZE; moving the city towards
local, distributed and fossil-fuel-free energy
systems; and achieving and sustaining significant
greenhouse gas reductions.
Buildings that use natural gas be made net zero with
on-site or building-owned resources. They must
have a market to allow excess renewable energy to
be sold to other buildings to offset the gas
consumption.
Minimizing the use of natural gas in new buildings
facilitates the long-term achievement of a sizeable
population of net zero buildings.
Commercial
and
Residential
2022
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ATTACHMENT B: OVERVIEW OF ENERGY AND GREEN CODES
Many components of the long-term strategy, as well as the short-term updates, rely on the
national suite of building and energy codes. This section provides background information on
those codes, definitions of key terms that are used throughout this memo, and a brief history of
Boulder’s energy codes.
The International Code Council (ICC) publishes an extensive series of model codes every three
years. In Colorado, these codes can then be adopted by local jurisdictions along with
modifications or exclusions, as desired. The International Energy Conservation Code (IECC) and
the International Green Construction Code (IgCC) are two such codes, and both are based on
standards developed by the America Society of Heating, Refrigerating and Air-Conditioning
Engineers (ASHRAE).
Table 6: Summary of National Energy and Green Codes
National Code International Energy Conservation
Code (IECC)
International Green Construction
Code (IgCC)
Scope
Building energy performance – applies
to both commercial and residential
buildings
“Green Code” addressing many aspects
of sustainability beyond energy; applies
only to commercial and high-rise (>3
stories) residential buildings
Use in Boulder
Code
Residential: IECC 2012 with local
amendments (Green Building and Green
Points)
Commercial: 30 percent more stringent
than IECC 2012
Not currently adopted
Alternate
compliance via
ASHRAE
Commercial: 30% more stringent than
ASHRAE 90.1-2010
ASHRAE 189.1 (2014 is equivalent to
IgCC 2015)
Important
Notes
IECC 2015 is only slightly more
stringent than the 2012 version4, and still
far less stringent than Boulder’s current
codes. IECC 2018 is expected to have
more significant updates and changes
when released.
IgCC 20185 will be merged with the
ASHRAE Standard 189.1-2017,
reducing confusion and pulling the best
aspects from both codes.
4 IECC 2015 compared to IECC 2012: 8.7% more stringent for commercial buildings and 0.73% more
stringent for residential buildings (according to Department of Energy)
5 Planned for release in late 2017
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While the IgCC is now available to provide green code language for commercial buildings, there
is still no suitable national model code6 for low-rise residential buildings. There are also many
voluntary residential green building programs, but most of them have third-party evaluators, cost
money to participate in and verify, have their own compliance guidelines and were not designed
to be “codified” (e.g., LEED for Homes, etc.) As a result, Boulder will continue to update and
evolve its residential green building code, the Green Building and Green Points program.
Pathways for Compliance
Energy codes have traditionally included at least two paths to compliance, prescriptive and
performance (see figure below). More recently, an additional option of outcome-based energy
codes has emerged. Mandatory requirements must be met regardless of which path is chosen.
Figure 3: Energy Code Pathways for Compliance
One limitation to both prescriptive and performance pathways is that they only address
efficiency characteristics of building design. Studies have shown that these design aspects only
account for 50 percent or less of the total energy consumption of the building. Characteristics
that are just as important include good building maintenance, efficient process and plug loads,
and operating practices by occupants and building staff.
To account for the energy performance of the entire building as used after occupancy, the
addition of outcome-based compliance is being explored for commercial buildings. This is an
approach that uses performance modeling to establish an energy consumption target during the
design stage, but final compliance is shown by monitoring of a building’s energy consumption
6 National Green Building Standard (NGBS) is the only known option, but is not recommended because the
energy chapter is not set up to guide builders to reach NZE and because it requires that certification is achieved
through the Home Innovations Research Lab, a subsidiary of the National Association of Home Builders.
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over a period of time (typically one year) following full occupancy. A building that exceeds the
target energy consumption established at the design stage must then take corrective actions to
reduce consumption. This type of code is currently being evaluated for inclusion in IgCC, IECC,
and in several jurisdictions. It is as also being piloted in Seattle as an optional compliance path
with a lower energy target than the performance path alone (link to 2014 ACEEE paper on
Seattle’s program). Outcome-based codes verify and guarantee that new buildings are actually
performing to the efficiency levels to which they were designed, but they also feature more
complicated compliance verification and contract structures, as compliance responsibility is
spread over multiple parties, including building occupants.
Metrics for Energy Code Stringency and Compliance
As the energy codes become more stringent, new methods of showing compliance or describing
stringency are evolving. As a result, several metrics have been established to compare energy
code stringency. These metrics will be referred to later in this memo.
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Table 7: Metrics and Energy Rating Scales
EUI (Energy Use Intensity): the total annual
energy used per square foot of gross floor area.
It is expressed in unit of kBtus (thousand British
thermal units) per square foot per year (kBtu/ft2-
yr).
HERS (Home Energy Rating System): A
nationally recognized index created by
RESNET and used as the industry standard to
measure the energy efficiency of a house. It is a
scale where 0 is a NZE house and 100 is the
energy consumption of a typical new
construction house that meets the IECC 2006
for energy efficiency.
ERI (Energy Rating Index)7: The ERI is
essentially a non-trademarked equivalent of the
HERS index. It is used as the scale for
establishing the performance path target by the
current version of the IECC for low-rise
residential buildings. Current Boulder
residential energy code requires a HERS
score/ERI ranging from 25 to 60, depending on
house size.
zEPI (Zero Energy Performance Index): This
is a scale for commercial buildings that is
similar to the ERI for residential buildings. This
scale also uses 0 for NZE buildings, but a score
of 100 is representative of the EUI of typical
existing building (opposed to new construction)
from the 2003 CBECS8 data. The current
Boulder energy code is equivalent to a zEPI
score of 38.
The metrics described the figure above can help establish more stringent energy code
requirements by specifying a lower zEPI or HERS/ERI requirement, thereby moving toward
NZE. By using these metrics, the comparison with energy code requirements throughout the
country is possible, regardless of which model code is adopted. However, compliance with the
commercial energy code requires modeling the energy usage of the reference building. This can
vary by building type, floor area and other factors. In the future, there is an opportunity to
simplify the commercial energy codes greatly by stating energy targets by building usage in
7 Because ERI is the metric used in national energy codes, the city will use this term in place of HERS.
8 Commercial Building Energy Consumption Survey – The Energy Information Administration (EIA) conducts
a survey of existing building energy use by building type and climate zone to form this dataset.
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terms of Energy Use Intensity (EUI), which then eliminates the need for modeling a fictitious
reference building.
Brief History of the City’s Energy Codes
The city has a long history of “green” (also referred to as “above” or “sustainability”) code
programs, and more recently, it has acquired a reputation of boldly adopting aggressive energy
code requirements. Below is a summary and brief timeline of code and policy adoption that has
put the city at the forefront in progressive and stringent building and energy code requirements,
with supporting programs such as Energy Smart, SmartRegs, and the Building Performance
Program.
Table 8: Overview of Boulder Energy Code History
Currently, the city evaluates and amends the latest national codes on a three-year cycle, and
usually adopts the newest suite of national/international code every six years. Because the city
has not yet adopted a national green building code, such as the IgCC for commercial buildings,
other portions of the city’s codes and Design Standards currently address many non-energy
sustainability issues (such as transportation and water). Please refer to Attachment A in the July
19, 2016 Information Packet Memo for a more complete history of the city’s residential and
commercial energy codes, including a comparison of their stringency to other energy codes.