Basis of Design Overview

The Basis of Design section contains project-wide settings that affect how HVAKR calculates loads, airflows, and equipment sizing. These settings establish the design parameters for your project.

Sections

General Information

Project details: the project picture, address, project number, project type, and construction type, plus tables for contacts, dates and deadlines, codes and standards, and special constraints. Setting the address looks up the project’s location and climate zone. The app sidebar labels this tab General.

Weather

Weather station selection and design conditions. HVAKR uses ASHRAE or CIBSE weather data to determine outdoor design temperatures for heating and cooling calculations.

Building Data

Set the building’s Conductive Time Series (CTS) data and define the thermal properties of your building envelope:

• Building CTS data, an optional building name and description, and read-only totals for floor area, volume, levels, and occupancy
• Wall types with U-values and construction details
• Roof types with U-values and construction details
• Slab types with F-factors for perimeter heat loss
• Window types with U-values, solar heat gain coefficients, and infiltration rates
• Door types with U-values and infiltration behavior

Space Types

Configure typical space characteristics:

• Indoor design conditions (cooling and heating setpoints and relative humidity)
• Ventilation, infiltration, and exhaust requirements
• People density (people per 1000 ft² or per 10 m²), people, lighting, and equipment loads
• Usage schedules

System Types

Define project-wide system design parameters:

• A system description for reports
• Duct types with sizing criteria (max velocity, max pressure drop, max height, liner thickness)
• Fitting loss coefficients (Cʟ) for elbows, transitions, and wyes
• Register criteria per space type (register models and max flow rate, velocity, and NC for supply, return, and exhaust)

Sheet Library

Manage floor plan drawings:

• Upload PDF or DXF files
• Check the Sheet Type, Sheet Number, and Scale that HVAKR fills in, and calibrate scale for accurate measurements
• Upload a newer revision of a sheet and compare versions

You place each sheet on a level in Building Model > Sheets, not in the Sheet Library.

Impact on Calculations

Changes to the Basis of Design automatically update calculations throughout your project:

• Weather changes affect heating and cooling loads
• Envelope properties affect transmission losses and solar gains
• Space type changes affect indoor setpoints, internal gains, and ventilation, infiltration, and exhaust requirements
• System type changes affect duct sizing, duct pressure losses, and register selection

Best Practices

1. Configure weather first - This ensures accurate design conditions
2. Define envelope types - Set up wall, window, and roof types before modeling
3. Create space types - Define typical spaces for your building type
4. Set up system types - Define duct types and register criteria before you lay out ducts. Configure each system’s equipment in System Design > Configuration

Reusing Configurations

Three mechanisms help you avoid re-entering common configurations:

• ASHRAE libraries - Pick each wall, roof, and window type’s Mass Data from built-in ASHRAE constructions. The book icon beside a field opens ASHRAE reference values. It does not fill in the field; enter the value you choose
• Import - The Import button on each type table opens a drawer with HVAKR Templates, My Templates, and My Active Projects tabs
• Data Sources - When you create a project, Include Space Type Templates, Include Climate Zone Minimum Envelope Types (Recommended), and Include Duct Type Templates add starting space types, envelope types, and duct types