[Code of Federal Regulations]
[Title 10, Volume 3]
[Revised as of January 1, 2001]
From the U.S. Government Printing Office via GPO Access
[CITE: 10CFR435.112]
[Page 611-616]
TITLE 10--ENERGY
CHAPTER II--DEPARTMENT OF ENERGY
PART 435--ENERGY CONSERVATION VOLUNTARY PERFORMANCE STANDARDS FOR NEW BUILDINGS; MANDATORY FOR FEDERAL BUILDINGS--Table of Contents
Subpart A--Voluntary Performance Standards for New Commercial and Multi-
Family High Rise Residential Buildings; Mandatory for Federal Buildings
Sec. 435.112 Building energy compliance alternative.
12.1 General
12.1 This section provides an alternative path for compliance with
the standards that allow for greater flexibility in the design of energy
efficient buildings using an annual energy target method. This path, as
does the path used in section 11.0, provides an opportunity for the use
of innovative designs, materials, and equipment such as daylighting,
passive solar heating, heat recovery, and thermal storage as well as
other applications of off-peak electrical energy where they cannot be
adequately evaluated by the prescriptive or system performance methods
found in sections 3.4, 3.5, 5.4, 5.5, 7.4., and 9.4.
12.1.2 The Building Energy Use Budget Target alternative may be
used as an option to the Building Energy Cost Budget method in section
11.0 and is to be used in lieu of the prescriptive and system
performance methods and in conjunction with sections 3.3, 4.3, 5.3, 6.3,
7.3, 8.3, 9.3 and 10.3.
12.1.3 Compliance under this section is demonstrated by showing
that the calculated annual energy usage for the Proposed Design is less
than or equal to a calculated Energy Use Budget. (See Figure 12-1). A
life-cycle cost economic analysis is required to evaluate alternative
fuel sources and energy reduction strategies. The procedures in this
chapter are intended only for establishing design compliance, and are
not intended to be used either to predict, document or verify annual
energy consumption or annual energy costs.
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[GRAPHIC] [TIFF OMITTED] TC04OC91.238
12.1.4 Compliance under the Building Energy Use Budget method
requires a detailed energy analysis, using a conventional simulation
tool, of the Proposed Design. A life-cycle cost analysis shall be used
to select the fuel source for the HVAC systems, service hot water, and
process loads from available alternatives. The Annual Energy Consumption
of the Proposed Design with the life-cycle cost-effective fuel selection
is calculated to determine the modeled energy consumption, called the
Design Energy Use.
12.1.5 The Design Energy Use is defined as the energy that is
consumed within the five foot line of a proposed building per
ft2 over a 24 hour day, 365-day year period and specified
operating hours. The calculated Design Energy
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Use is then compared to a calculated Energy Use Budget.
12.1.6 Compliance. The Energy Use Budget is determined by
calculating the annual energy usage for a Reference or Prototype
Building that is configured to comply with the provisions of section
11.0 for such buildings, except that the fuel source(s) of the Prototype
or Reference Building shall be the same life-cycle cost-effective
source(s) selected for the Proposed Design. If the Design Energy Use is
less than or equal to the Energy Use Budget then the proposed design
complies with these standards.
12.1.7 This section provides instructions for determining the
Design Energy Use and for calculating the Energy Use Budget. The Energy
Use Budget is the highest allowable calculated annual energy consumption
for a specified building design. Designers are encouraged to design
buildings whose Design Energy Use is lower than the Energy Use Budget.
Incorporated in this section is an optional life-cycle cost economic
analysis procedure that may be used by the designer to examine the
economic feasibility of all energy design alternatives and to produce a
more optimum design.
12.2 Determination of the Annual Energy Budget
12.2.1 The Energy Use Budget shall be calculated for the
appropriate Prototype or Reference Building in accordance with the
procedures prescribed in section 11.2 with the following exceptions: The
Energy Use Budget shall be stated in units of Btu/ft2. yr and
the simulation tool shall segregate the calculated energy consumption by
fuel type producing an Energy Use Budget for each fuel (the fuel
selections having been made by a life cycle cost analysis in determining
the proposed design).
12.2.2 The Energy Use Budget (EUB) is calculated similarly for the
Reference or Prototype Building using the following equation:
EUB=EUB1 x f1+EUB2 x f2+ . .
. . . +EUBi x fi
Equation 12-1
Where EUB1, EUB2, . . . EUBi are the
calculated annual energy targets for each fuel used in the Reference or
Prototype building and f1, f2, . . . fi
are the energy conversion factors given in Table 12-1. In lieu of case
by case calculation of the Energy Use Budget, the designer may construct
Energy Use Budget tables for the combinations of energy source(s) that
may be considered in a set of project designs, such as electric heating,
electric service water, and gas cooling or oil heating, gas service
water and electric cooling. The values in such optional Energy Use
Budget tables shall be equal to or less than the corresponding Energy
Use Budgets calculated on a case by case basis according to this
section. Energy Use Budget tables shall be constructed to correspond to
the climatic regions and building types in accordance with provisions
for Prototype or Reference Building models in section 11.0 of these
standards.
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[GRAPHIC] [TIFF OMITTED] TC04OC91.240
12.3 Determination of the Design Energy Use
12.3.1 The Design Energy Use shall be calculated by modeling the
Proposed Design using the same methods, assumptions, climate data, and
simulation tool as were used to establish the Energy Use Budget, but
with the design features that will be used in the final building design.
The simulation tool
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used shall segregate the calculated energy consumption by fuel type
giving an annual Design Energy Use for each fuel. The sum of the Design
Energy Uses multiplied by the fuel conversion factors in Table 12-1
yields the Design Energy Use for the proposed design:
DEU=DEU1 x f1+DEU2 x f2+ . .
. . +DEUi x fi
Equation 12-2
Where f1, f2, . . . fi are the fuel
conversion factors in Table 12-1.
12.3.2 Required Life Cycle Cost Analysis for Fuel Selection
12.3.2.1 Fuel sources selected for the Proposed Design and
Prototype or Reference buildings shall be determined by considering the
energy cost and other costs and benefits that occur during the expected
economic life of the alternative.
12.3.2.2 The designer shall use the procedures set forth in subpart
A of 10 CFR part 436 to make this determination. The fuel selection life
cycle cost analysis shall include the following steps:
12.3.2.2.1 Determine the feasible alternatives for energy sources
of the Proposed Design's HVAC systems, service hot water, and process
loads.
12.3.2.2.2 Model the Proposed Design including the alternative HVAC
and service water systems and conduct an annual energy analysis for each
fuel source alternative using the simulation tool specified in this
section. The annual energy analysis shall be computed on a monthly basis
in conformance with section 11.0 of these standards with the exception
that all process loads shall be included in the calculation. Separate
the output of the analysis by fuel type.
12.3.2.2.3 Determine the unit price of each fuel using information
from the utility or other reliable local source. During rapid changes in
fuel prices it is recommended that an average fuel price for the
previous twelve months be used in lieu of the current price. Calculate
the annual energy cost of each energy source alternative in accordance
with procedures in section 11.0 for the Design Energy Cost. Estimate the
initial cost of the HVAC and service water systems and other initial
costs such as energy distribution lines and service connection fees
associated with each fuel source alternative. Estimate other costs and
benefits for each alternative including, but not necessarily limited to,
annual maintenance and repair, periodic and one time major repairs and
replacements and salvage of the energy and service water systems. Cost
estimates shall be prepared using professionally recognized cost
estimating tools, guides and techniques.
12.3.2.2.4 Perform a life cycle cost analysis using the procedure
specified in section 12.3.2.
12.3.2.2.5 Compare the total life cycle cost of each energy source
alternative. The alternative with the lowest total life-cycle cost shall
be chosen as the energy source for the proposed design.
12.4 Compliance
12.4.1 Compliance with this section is demonstrated if the Design
Energy Use is equal to or less than the Energy Use Budget.
DEUEUB
Equation 12-3
12.4.2 The energy consumption shall be measured at the building
five foot line for all fuels. Energy consumed from non-depletable energy
sources and heat recovery systems shall not be included in the Design
Energy Use calculations. The thermal efficiency of fixtures, equipment,
systems or plants in the proposed design shall be simulated by the
selected calculation tool.
12.5 Standard Calculation Procedure
12.5.1 The Standard Calculation Procedure consists of methods and
assumptions for calculating the Energy Use Budgets for Prototype and
Reference Buildings and the Design Energy Use for the Proposed Design.
In order to maintain consistency between the Energy Use Budgets and the
Design Energy Use, the input assumptions stated in section 11.5 are to
be used.
12.5.2 The terms Energy Cost Budget and Design Energy Cost or
Consumption used in section 11.0 correlate to Energy Use Budget and
Design Energy Use, respectively, in section 12.0.
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12.6 The Simulation Tool
12.6.1 The criteria established in section 11.0 for the selection
of a simulation tool shall be followed when using the compliance path
prescribed in section 12.0.
12.7 Life Cycle Cost Analysis Criteria
12.7.1 The following life cycle cost criteria applies to the fuel
selection requirements of this chapter and to option life cycle cost
analyses performed to evaluate energy conservation design alternatives.
The fuel source(s) selection shall be made in accordance with the
requirements of subpart A of 10 CFR part 436. The implementation
calculations for the methodology of subpart A of 10 CFR part 436 is
provided in National Bureau of Standards Handbook 135 entitled ``Life
Cycle Cost Manual for the Federal Energy Management Program.'' When
performing life cycle cost analyses of optional energy conservation
opportunities the designer may use the life cycle cost procedures of
subpart A of 10 CFR part 436 or OMB Circular A-94 or an equivalent
procedure that meets the assumptions listed below:
12.7.1.1 The economic life of the Prototype Building and Proposed
Design shall be 25 years. Anticipated replacements or renovations of
energy related features and systems in the Prototype or Reference
Building and Proposed Design during this period shall be included in
their respective life cycle cost calculations.
12.7.1.2 The designer shall follow established professional cost
estimating practices when determining the costs and benefits associated
with the energy related features of the Prototype or Reference Building
and Proposed Design.
12.7.1.3 All costs shall be expressed in current dollars. General
inflation shall be disregarded. Differential escalation of prices
(prices estimated to rise faster or slower than general inflation) for
energy used in the life cycle cost calculations shall be those in effect
at the time of the life cycle cost calculations as published by the
Department of Energy's Energy Information Administration.
12.7.1.4 The economic effects of taxes, depreciation and other
factors not consistent with the practices of subpart A of 10 CFR part
436 shall not be included in the life cycle cost calculation.
Subpart B--Voluntary Performance Standards for New Non-Federal Residential
Buildings [Reserved]