openstudio-standards

BTAP Costing Framework

Overview

The BTAP Costing Framework is one of the most comprehensive building lifecycle cost analysis systems available, providing detailed economic analysis for all building systems with Canadian-specific regional cost variations. This framework enables complete building cost estimation from conceptual design through detailed analysis, with integration for energy conservation measure (ECM) cost-benefit analysis.

Architecture Overview

Core Components

• Main Costing Engine (btap_costing.rb) - Central cost calculation and regional interpolation
• Database System (costing_database_wrapper.rb) - Cost data management and validation
• Component Costing Modules (9 specialized modules) - Building system-specific cost calculations
• Cost Database (common_resources/) - Comprehensive Canadian cost data
• Testing Framework - Automated validation and regression testing
• Workflow Integration - OpenStudio measure and NECB standards integration

Data Flow Architecture

Building Model → Component Analysis → Regional Cost Factors → Database Lookup → Cost Calculation → Results Aggregation

Main Costing Engine

btap_costing.rb - Core System

BTAPCosting Class

Primary costing engine with regional cost factor integration

Key Features:

• Regional Cost Interpolation: Distance-based cost interpolation between Canadian cities
• Database Generation: Automated cost database creation for all Canadian locations
• Cost Auditing: Comprehensive cost validation and verification
• Mechanical Integration: Integration with mechanical system sizing data

Core Methods:

Regional Cost Analysis

# Get cost factors for specific location
get_regional_cost_factors(location)

# Find closest cost database location  
get_closest_cost_location(lat, lon)

# Distance-based interpolation between locations
interpolate(target_location, reference_locations, values)

Database Management

# Load complete cost database
load_database()

# Validate all cost data for consistency
validate_database()

# Generate regional cost databases
generate_construction_cost_database_for_all_cities()

Cost Calculation

# Add individual cost items to building total
add_costed_item(category, description, quantity, unit_cost, total_cost)

# Process list of cost items
cost_list_items(cost_item_array)

SimpleLinearRegression Class

Mathematical utility for cost interpolation calculations

Purpose: Provides statistical interpolation for regional cost variations Usage: Used internally by BTAPCosting for distance-based cost adjustments

Component Costing Modules

Building Systems Costing

1. Envelope Costing (envelope_costing.rb)

Building envelope component cost analysis

Components Covered:

• Exterior Walls: All construction types and insulation levels
• Roofs: Flat and sloped roofs with various membrane and insulation systems
• Foundations: Basement walls, slab-on-grade, crawl spaces
• Windows and Doors: Various performance levels and frame types
• Air Sealing: Building envelope airtightness measures

Integration Points:

• Construction assembly performance requirements
• Regional material and labor cost variations
• Energy code compliance cost implications

2. HVAC System Costing (heating_cooling_costing.rb)

Complete HVAC equipment and system costing

Equipment Categories:

• Heating Equipment: Boilers, furnaces, heat pumps, electric heating
• Cooling Equipment: Chillers, rooftop units, split systems, evaporative cooling
• Distribution Systems: Ductwork, piping, pumps, fans
• Controls: Thermostats, building automation, advanced controls
• Specialized Systems: Radiant systems, displacement ventilation

Costing Methodology:

• Equipment capacity-based costing with performance tier adjustments
• Installation complexity factors for different building types
• Regional labor rate variations
• Commissioning and testing cost inclusions

3. Lighting System Costing (lighting_costing.rb & led_lighting_costing.rb)

Traditional Lighting (lighting_costing.rb)

• Fixture Costs: All standard commercial fixture types
• Control Systems: Occupancy sensors, daylight dimming, time controls
• Installation: Electrical connections, mounting, commissioning

LED Lighting Upgrades (led_lighting_costing.rb)

• LED Conversion Costs: Retrofit and new installation LED systems
• Payback Analysis: Energy savings vs. capital cost analysis
• Control Integration: Advanced LED controls and dimming systems
• Maintenance Savings: LED lifecycle cost advantages

4. Ventilation System Costing (ventilation_costing.rb)

Air handling and ventilation system economics

System Components:

• Air Handling Units: Various sizes and efficiency levels
• Ductwork Systems: Supply, return, and exhaust ductwork
• Filtration: Standard and high-efficiency filtration systems
• Ventilation Controls: CO2 sensors, variable speed drives

5. Service Hot Water Costing (shw_costing.rb)

Complete service water heating system analysis

System Elements:

• Water Heaters: Gas, electric, heat pump, solar thermal systems
• Distribution Systems: Piping, insulation, circulation pumps
• Controls: Temperature controls, circulation controls, timer systems
• Efficiency Measures: Heat recovery, high-efficiency equipment

6. Advanced System Costing

Demand Controlled Ventilation (dcv_costing.rb)

• CO2 Sensors: Cost and installation of occupancy-based ventilation controls
• Control Systems: Integration with building automation systems
• Energy Savings: Ventilation energy reduction economic analysis

Daylighting Controls (daylighting_sensor_control_costing.rb)

• Daylight Sensors: Various sensor types and placement strategies
• Dimming Controls: Continuous and stepped dimming systems
• Integration Costs: Connection to lighting control systems

Natural Ventilation (nv_costing.rb)

• Operable Windows: Automated and manual window systems
• Control Systems: Temperature and wind sensors, automated controls
• Mixed-Mode Integration: Natural and mechanical ventilation integration

Ground-Mounted PV (pv_ground_costing.rb)

• Solar Panels: Various efficiency levels and mounting systems
• Electrical Systems: Inverters, electrical connections, grid integration
• Installation: Site preparation, mounting structures, commissioning

Cost Database System

Database Wrapper (costing_database_wrapper.rb)

CostingDatabase Class

Central database management and validation system

Key Functionality:

• Database Loading: Load cost data from CSV resources
• Data Validation: Comprehensive validation of all cost data
• Database Access: Thread-safe access to cost information
• Schema Enforcement: Ensure data structure consistency

Critical Methods:

# Load database from CSV resources
load_database_from_resources()

# Validate complete database for consistency
validate_database()

# Validate construction set definitions
validate_constructions_sets()

# Validate HVAC equipment data
validate_ahu_items_and_quantities()

Cost Database Structure (common_resources/)

Core Cost Data

• costs.csv: Base construction and equipment costs
• costs_local_factors.csv: Regional cost adjustment factors for all Canadian provinces/territories
• locations.csv: Geographic coordinates and regional data for cost interpolation

Material Databases

• materials_opaque.csv: Insulation, structural, and finish materials
• materials_glazing.csv: Windows, glazing, and frame materials
• materials_lighting.csv: Lighting fixtures, lamps, and control equipment
• materials_hvac.csv: HVAC equipment, components, and installation materials

Construction and Assembly Data

• constructions_opaque.csv: Wall, roof, floor, and foundation assemblies
• constructions_glazing.csv: Window and door assembly definitions
• construction_sets.csv: Complete building envelope construction sets
• ConstructionProperties.csv: Thermal and physical properties with cost data
• Constructions.csv: Detailed construction assembly specifications

Equipment and System Data

• hvac_vent_ahu.csv: Air handling unit specifications, capacities, and costs
• lighting_sets.csv: Complete lighting system packages
• lighting.csv: Individual lighting fixture and component costs

Regional Cost System

Canadian Regional Integration

Provincial Cost Factors

All Canadian provinces and territories included:

• British Columbia, Alberta, Saskatchewan, Manitoba
• Ontario, Quebec, New Brunswick, Nova Scotia, Prince Edward Island
• Newfoundland and Labrador, Northwest Territories, Nunavut, Yukon

Cost Interpolation Methodology

• Distance Calculation: Great circle distance between project location and reference cities
• Weight Calculation: Inverse distance weighting for cost factor interpolation
• Factor Application: Apply interpolated factors to base costs
• Validation: Ensure interpolated costs fall within reasonable ranges

Regional Variations Captured

• Labor Costs: Regional labor rate differences
• Material Costs: Transportation and availability impacts
• Market Conditions: Regional construction market factors
• Climate Adjustments: Cold weather construction impacts

Testing and Validation Framework

Automated Testing System

Test Execution (test_run_costing_tests.rb)

Main test runner for comprehensive costing validation

Testing Categories:

• Component Costing Tests: Validate each building system costing module
• Database Tests: Ensure cost database integrity and completeness
• Regional Factor Tests: Validate cost interpolation across all Canadian locations
• Integration Tests: Test costing integration with building models

Parallel Testing (parallel_tests.rb)

Large-scale test execution for comprehensive validation

Capabilities:

• Multi-Core Testing: Parallel test execution for faster validation
• Regression Testing: Compare results against established baselines
• Performance Testing: Validate costing calculation performance
• Coverage Analysis: Ensure comprehensive test coverage

Test Management

• copy_test_results_files_to_expected_results.rb: Test result management and baseline updates
• test_run_all_test_locally.rb: Local development testing framework

Reference Data Validation

NECB Reference Buildings (necb_reference_runs.csv)

Comprehensive cost validation using Canadian reference buildings

Validation Coverage:

• All major Canadian building types
• Multiple climate zones
• Various building sizes and complexities
• Integration with NECB energy standards

Mechanical System Validation (mech_sizing.json)

HVAC system sizing and costing validation data

Content:

• Equipment capacity ranges and costs
• Installation complexity factors
• Regional installation cost variations
• Performance verification data

Utility Cost Integration (neb_end_use_prices.csv)

Canadian utility rate integration for lifecycle cost analysis

Data Sources:

• National Energy Board utility rate data
• Provincial utility rate structures
• Time-of-use pricing where applicable
• Regional rate variations

Workflow Integration

OpenStudio Measure Integration (btap_measure_helper.rb)

BTAPMeasureHelper Class

Integration with OpenStudio measure framework

Key Features:

• Argument Validation: Validate measure arguments for costing calculations
• Hash Conversion: Convert measure arguments to costing parameters
• Type Validation: Ensure argument types match costing requirements

BTAPMeasureTestHelper Class

Testing framework for measure integration

Testing Capabilities:

• Argument Range Testing: Validate argument ranges and defaults
• Model Creation: Create NECB prototype models for testing
• Measure Execution: Run measures with costing integration
• Result Validation: Validate costing results from measure execution

BTAP Workflow Integration (btap_workflow.rb)

Integration with larger BTAP analysis workflows

Workflow Steps:

• Model Analysis: Extract building characteristics for costing
• Component Identification: Identify all building systems and components
• Regional Analysis: Determine appropriate regional cost factors
• Cost Calculation: Calculate costs for all building systems
• Results Integration: Integrate costs with energy and performance analysis

File-Based Costing (cost_building_from_file.rb)

Automated costing from building definition files

Capabilities:

• Batch Processing: Cost multiple buildings from file definitions
• Standardized Input: Consistent building definition format
• Automated Analysis: Minimal user intervention required
• Results Export: Standardized costing result formats

Usage Patterns

Basic Costing Workflow

1. Initialize Costing System

# Create costing object with database loading
costing = BTAPCosting.new
costing.load_database

# Validate database integrity  
costing.validate_database

2. Determine Regional Factors

# Get regional cost factors for project location
location = "Toronto, ON"
cost_factors = costing.get_regional_cost_factors(location)

# Or use coordinates for precise interpolation
lat, lon = 43.7, -79.4
closest_location = costing.get_closest_cost_location(lat, lon)

3. Calculate Component Costs

# Example: Envelope costing
envelope_costs = calculate_envelope_costs(model, cost_factors)

# Example: HVAC system costing  
hvac_costs = calculate_hvac_costs(model, cost_factors)

# Aggregate all system costs
total_cost = envelope_costs + hvac_costs + lighting_costs + ...

Advanced Costing Analysis

1. ECM Cost-Benefit Analysis

# Calculate baseline building cost
baseline_cost = calculate_total_building_cost(baseline_model, location)

# Calculate improved building cost
improved_cost = calculate_total_building_cost(improved_model, location)

# Determine incremental cost
ecm_cost = improved_cost - baseline_cost

# Calculate payback with energy savings
payback_period = ecm_cost / annual_energy_savings

2. Regional Cost Comparison

# Compare costs across multiple Canadian cities
cities = ["Vancouver, BC", "Calgary, AB", "Toronto, ON", "Montreal, QC"]
costs = {}

cities.each do |city|
  cost_factors = costing.get_regional_cost_factors(city)
  costs[city] = calculate_total_building_cost(model, cost_factors)
end

3. Parametric Cost Analysis

# Analyze cost impacts of different design parameters
insulation_levels = [RSI_2, RSI_3, RSI_4, RSI_5]
costs = []

insulation_levels.each do |r_value|
  modified_model = adjust_envelope_insulation(model, r_value)
  cost = calculate_envelope_costs(modified_model, cost_factors)
  costs << {r_value: r_value, cost: cost}
end

Integration with NECB Standards

Standards Compliance Costing

The costing framework fully integrates with NECB (National Energy Code for Buildings) requirements:

• Baseline Compliance: Cost of meeting minimum NECB requirements
• Above-Code Measures: Incremental costs for exceeding code requirements
• System Selection: Cost implications of different NECB-compliant HVAC systems
• Regional Variations: How NECB compliance costs vary across Canadian climate zones

Energy Conservation Measures (ECMs)

• NECB ECM Library: Pre-defined ECMs with established cost data
• Custom ECM Analysis: Tools for analyzing custom energy conservation measures
• Lifecycle Cost Integration: Complete economic analysis including energy savings

Development Guidelines

Adding New Component Costing

1. Create Component Module

# Create new file: new_system_costing.rb
class NewSystemCosting
  def self.calculate_costs(model, cost_factors, options = {})
    # Implement costing logic
  end
end

2. Add Cost Database Entries

• Update appropriate CSV files in common_resources/
• Add equipment/material specifications
• Include regional cost factors
• Validate database integrity

3. Create Tests

• Add component-specific test cases
• Test regional cost variations
• Validate against known project costs
• Include in automated test suite

4. Integration

• Integrate with main costing workflow
• Add to cost aggregation logic
• Update documentation
• Include in validation framework

Testing Requirements

1. Component Tests

• Test each costing module independently
• Validate cost calculations against manual calculations
• Test regional factor applications
• Validate database lookups

2. Integration Tests

• Test complete building costing workflows
• Validate cost aggregation logic
• Test integration with NECB standards
• Validate ECM cost calculations

3. Regression Tests

• Maintain baseline cost results for reference buildings
• Detect unintended cost calculation changes
• Validate database updates don't break existing functionality
• Performance regression testing

Key Benefits for LLM Development

Clear System Understanding

• Component Relationships: Understand how 9 costing modules interact
• Data Flow: Clear path from building model to final costs
• Regional Logic: How Canadian cost variations are handled
• Integration Points: Where costing connects to NECB standards and BTAP workflow

Safe Modification Guidelines

• Database Schema: Understand CSV structure to prevent data corruption
• Regional Factor Logic: Critical cost interpolation algorithms
• Testing Framework: How to validate changes don't break existing functionality
• API Boundaries: Clear interfaces between costing modules

Established Patterns

• Component Addition: Template for adding new building system costing
• Data Updates: Process for updating cost databases safely
• Validation Requirements: What constitutes valid costing data
• Error Handling: How to handle missing data and edge cases

This comprehensive framework represents years of Canadian building cost analysis expertise and provides the foundation for sophisticated building economic analysis.