11.3      Analysis Procedure

This section is a summary of the analysis procedures used in demonstrating compliance with approved compliance software programs. Software users and those checking for enforcement should consult the most current version of the compliance software user’s manual and/or on-line help and associated compliance supplements for specific instructions on the operation of the compliance software. Although there are numerous requirements for each software input, the data entered into each software version may be organized differently from one vendor to the next. As a result, it is not possible in this summary to present all variables in their correct order or hierarchy for any one software version. The aim is to identify the procedures used to calculate the standard design energy budget and the TDV energy use of the proposed building.

11.3.1        General Procedure

Any compliance software version approved by the Energy Commission may be used to comply with the Energy Standards. The following steps are a general outline of the process:

1.   All detailed data for the building components must be collected including fenestration areas and energy properties; wall, door, roof/ceiling, and floor areas; construction assemblies; mass characteristics; equipment specifications; lighting; and service water heating information from the drawings and specifications.

2.   Although most compliance software requires the same basic data, some information and the manner in which it is organized may vary according to the particular software used. Refer to the compliance supplement that comes with each version of compliance software for additional details.

3.   Be sure that the correct climate information has been selected for the building site location (see Reference Appendix JA2). Compliance software also adjusts outside heating and cooling design temperatures for local conditions using ASHRAE design data that is also located in Reference Appendix JA2.

4.   Prepare an input file that describes the other thermal aspects of the proposed design according to the rules described in the software’s compliance supplement.

5.   Input values and assumptions must correctly correspond to the proposed design and conform to the required mandatory measures.

6.   Run the compliance software to automatically generate the energy budget of the standard design and calculate the energy use of the proposed design.    Computer Input Files

When creating any computer input file, use the space provided for the project title information to concisely and uniquely describe the building being modeled. User-designated names should be clear and internally consistent with other buildings being analyzed in the same project. Title names and explanatory comments should assist individuals involved in both the compliance and enforcement process.

11.3.2        Basic Data Entry    Elements Used in Compliance Software

The following elements are used by compliance software programs. These elements must be consistent with plans and specifications submitted in the building permit application:

1.   Opaque Walls: Each opaque exterior wall construction assembly, wall area, orientation, and tilt. Heat capacities, or characteristics necessary to determine the heat capacity (conductivity, mass, volume) of opaque exterior walls, must be included. Interior demising wall area and characteristics must also be input.

2.   Doors: All doors must be included.

3.   Opaque Roofs/Ceilings: Each opaque exterior roof/ceiling construction assembly, roof/ceiling area, solar reflectance, thermal emittance, orientation, and tilt. Heat capacity, or characteristics necessary to determine the heat capacity (conductivity, mass, volume) of opaque exterior roof/ceilings, must be included.

4.   Raised Floors and Slab Floors: Each floor construction assembly, including floor area.

5.   Fenestrations in Walls and Shading: Each vertical glass area, orientation, tilt, U-factor, Solar Heat Gain Coefficient (SHGC), and Visible Transmittance (VT).  The shading would be from permanently affixed shading devices, such as overhangs and fins.  The shading inputs would consist of depth, distance, and extension relative to the glass.

6.   Horizontal (Skylight) Fenestration: Each horizontal or skylight glass area, orientation, tilt, U-factor, SHGC, and VT.

7.   Ventilation Air: Ventilation (introduction of outside air) values in cfm/ft².

8.   Fan Power: Fan power must be included. Fan power should be based on shaft brake horsepower at the equipment’s rated condition (modeled horsepower must be substantiated by information contained in the construction documents).

9.   Cooling and Heating Efficiency: The efficiency of the equipment included in the proposed design at AHRI conditions.

10.  HVAC System Type: The basic type of the cooling and heating system (multiple zones or single zone) and the heating system fuel type (fossil fuel or electric). Note that some projects may have different system types serving separate zones.

11.  Sensible and Total Cooling System Capacity: Sensible and total output capacity of the cooling system at AHRI conditions.

12.  Heating System Capacity: The output capacity of the heating system.

13.  Indoor Lighting: Lighting loads and modeling non-mandatory controls for credit.

14.  Water Heating: The water heating capacity, volume, and efficiency (including any solar thermal contribution).

15.  Other System Values: All other space conditioning system components, process loads, or any other mechanical system that impacts the building energy performance must be included in the input file.

Refer to the compliance software user’s manual for more detailed information on how each of the above values is used by the software.

11.3.3        Calculating TDV Energy

The proposed and standard design TDV energy budgets are separated into a compliance total, which is the basis for building compliance with the performance method, and a total building energy usage, which adds receptacle, process and other non-regulated energy usage.

The compliance total TDV energy can be summarized into three main components:

1.  The space conditioning energy use.

2.  The indoor lighting energy use.

3.  The service water heating energy use.

Non-regulated energy; process, receptacle, other lighting, and process motors; is treated as compliance neutral. The standard design will always match the proposed energy usage for these categories.

The proposed building energy budget is defined by §140.1(b) and includes the envelope, space conditioning and ventilation, indoor lighting, and water heating systems assigned to the building. The key component of calculating the TDV energy use of the proposed building is that if a feature of the building is not included in the building permit application, the energy use of that feature is equal to that of the standard energy budget defined in §140.1(a). That means that if a permit is submitted for a building shell (envelope only), and the performance approach is used to demonstrate compliance, trade-offs cannot be made between the envelope and the mechanical or lighting system.

The standard design budget is defined by replacing all of the energy features of the proposed building with a combination of the envelope features listed in the prescriptive package requirements in Tables 140.3 B or C of the Energy Standards.  Lighting and mechanical values associated with the building occupancy and design are defined in the Nonresidential ACM Reference Manual.    Space Conditioning Energy Budget

The space conditioning energy budget is automatically determined from the software’s user inputs and the corresponding elements of the proposed design. This budget is automatically re-calculated with each compliance run.    Lighting Energy Budget

The indoor lighting budget consists of the lighting power used by a building based on one of the following criteria:

1.   When no lighting plans or specifications are submitted for permit and the occupancy of the space is not known, the standard lighting power density is 0.40 W/ft².

2.   When no lighting plans or specifications are submitted for permit and the occupancy of the space is known, the standard lighting power is equal to the corresponding watt per ft² value derived in the Area Category Method of §140.6(c)2.

3.   When lighting plans and specifications are submitted for permit, the standard lighting power is equal to the corresponding total allowed lighting power (in watts) that was used in calculating the proposed lighting level which can be based on either the Area Category Method or the Tailored Method (§140.6(c)2 or 3). A complete set of lighting plans and prescriptive documents are required to use the Tailored Lighting Method in the performance approach. When this method is used to justify an increase in the allowed lighting watts, a lower lighting load in the proposed design cannot be modeled for credit. The standard design building uses the lesser of allowed Watts per ft² or actual lighting power to be installed in the building. The proposed design building uses the actual lighting power to be installed as detailed on the lighting plans. This value must be equal to or greater than the allowed Watts per ft².

For all occupancies except hotel guest rooms and high-rise residential dwelling units, the proposed lighting power is input into the software. For residential occupancies (hotel guest rooms or high-rise residential spaces), the compliance software will automatically set the proposed lighting power and the standard design lighting power at the same value as specified in the Nonresidential ACM Reference Manual.    Service Water Heating Energy Budget

The service water heating budget consists of the service water heating energy used by a building assuming the service water heating system meets both the mandatory and prescriptive requirements for water heating.

The service water heating TDV energy use is calculated using one of two methods:

1.  For nonresidential occupancies, the standard design service water heating system is determined as described in the Nonresidential ACM Reference Manual.

2.  For hotels, motels and high-rise residential spaces, the water heating TDV energy budget is calculated using the methods and assumptions documented in the Residential ACM Reference Manual.