Section 120.8(c). Basis of Design (BOD). A written explanation of how the design of the building systems meets the OPR shall be completed at the design phase of the building project, and updated as necessary during the design and construction phases. The Basis of Design document shall cover the following systems:
1. Heating, ventilation, air conditioning (HVAC) systems and controls
2. Indoor lighting system and controls
3. Water heating systems and controls
4. Covered processes
12.3
The Basis of Design (BOD) describes the building systems to be commissioned and outlines design assumptions not indicated in the design documents. The design team develops the BOD to describe how the building systems design meets the Owner’s Project Requirements (OPR), and why the systems were selected. The BOD is most effective when developed early in the project design and updated as necessary throughout the design process.
Compliance requires the completion of the BOD document, which should include the following:
1. Heating, Ventilation, Air Conditioning (HVAC) Systems and Controls
a. Provide narrative description of system – system type, location, control type, efficiency features, outdoor air ventilation strategy, indoor air quality features, environmental benefits, other special features.
b. Describe reasons for system selection – why chosen system is better than alternatives, considering issues such as comfort, performance, efficiency, reliability, flexibility, simplicity, cost, owner preference, site constraints, climate, maintenance, acoustics
c. Provide design criteria including the following:
− Load calculation method/software
− Summer outdoor design conditions, °F drybulb and °F wetbulb
− Winter outdoor design conditions, °F drybulb and °F wetbulb
− Indoor design conditions, °F drybulb cooling, %RH cooling;
°F drybulb heating, %RH heating
− Applicable codes, guidelines, regulations and other references used
− Load calculation assumptions
d. Sequence of Operations – operating schedules, setpoints, may refer to plans or specifications
e. Describe how system meets the OPR
2. Indoor Lighting System and Controls
a. Provide narrative description of system – type of fixtures, lamps, ballasts, controls
b. Describe reason for system selection – why chosen system better than alternatives, considering issues such as visual comfort, performance, efficiency, reliability, cost, flexibility, owner preference, color rendering, integration with daylighting, ease of control
c. Provide design criteria for each type of space including the following:
− Applicable codes, guidelines, regulations and other references used
− Illumination design targets (footcandles) and lighting calculation assumptions
d. Provide lighting power design targets for each type of space
− Title 24 lighting power allowance and lighting power design target (watts/ft²)
e. Describe how system meets the OPR
3. Water Heating Systems and Controls
a. Provide narrative description of system – system type, control type, location, efficiency features, environmental benefits, other special features
b. Describe reason for system selection – why chosen system is better than alternatives, considering issues such as performance, efficiency, reliability, space constraints, cost, utility company incentives, owner preference, ease of maintenance
c. Water heating load calculations
d. Describe how system meets the OPR
4. Covered Processes
a. Provide narrative description of system – type, performance, control type, energy savings, payback period
b. Describe reason for system selection – why chosen system is better than alternatives, considering issues such as performance, efficiency, reliability, flexibility, simplicity, expandability, cost, payback period, utility company incentives, owner preference
c. Sequence of Operation – operating schedules, setpoints, storage capacity
d. Describe how system meets the OPR
Enforcement
At their discretion, the building official confirms demonstrated compliance at Plan Review by:
a. Receipt of a copy of the BOD document (optional), or
b. Receipt of a form signed by the owner, owner’s representative, architect, engineer or designer of record, attesting that the BOD has been completed and meets the requirements of the OPR.