1.2 The EDGE Standard & Baseline Methodology

1.2 The EDGE Standard & Baseline Methodology

Exam Focus: Understanding how EDGE establishes location-specific baselines, how the virtual reference building is generated, and how calculations work across the three resource categories—Operational Energy, Operational Water, and Embodied Energy in Materials—is central to passing the EDGE Expert Exam.

The foundational principle of the EDGE green building system is quantitative performance benchmarking. Unlike point-based green building rating systems that reward points for specific design features, EDGE requires projects to demonstrate measurable percentage reductions against a localized virtual reference model.

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The Core 20/20/20 Rule

To achieve basic EDGE Certification, a project must achieve a minimum threshold of 20% resource reduction across three distinct environmental pillars compared to a local baseline building:

$\text{Minimum EDGE Threshold} = \begin{cases} \mathbf{20\%} & \text{Operational Energy Reduction} \\ \mathbf{20\%} & \text{Operational Water Reduction} \\ \mathbf{20\%} & \text{Embodied Energy Reduction in Materials} \end{cases}$

Every project must hit or exceed 20% in all three categories simultaneously. A project that achieves 50% energy savings and 40% water savings, but only 18% embodied energy savings in materials, fails to achieve EDGE Certification until the materials threshold reaches 20%.

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Baseline Methodology: How Local Baselines Are Created

A key innovation of EDGE is its automated baseline calculation engine. Rather than applying one international energy code uniformly worldwide, EDGE establishes location-specific, typology-specific baselines tailored to over 170 countries and thousands of individual cities.

Baseline Determination Factors

The EDGE baseline algorithms aggregate multiple data sources to reflect standard local building practices:

1. Local Building Regulations & Energy Codes: Standard municipal building codes, national energy efficiency regulations, and regional water standards.
2. Market Common Practice Data: Empirical data gathered by IFC research teams representing typical construction methods in a given country (e.g., single-pane clear glass vs. tinted glass, uninsulated brick walls vs. insulated concrete blocks).
3. Location-Specific Climate & Resource Data: For every city built into the software, EDGE stores monthly average wet- and dry-bulb temperature, monthly average outdoor wind velocity, monthly average outdoor humidity, solar radiation intensity, annual average rainfall, the carbon dioxide intensity of the electricity grid, and the average local cost of energy (by fuel type) and water.
4. Standard Operational Schedules & Occupancy Densities: Preset occupancy levels ($m^2/\text{person}$), internal heat gains from people and appliances, daily operating hours, and indoor thermostat setpoints based on building typology.

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The Virtual Reference Building Model

When an EDGE Expert creates a project in the EDGE App, the software automatically constructs a Virtual Reference Building (Baseline Model) behind the scenes.

Principles of the Virtual Reference Model

• Identical Geometry & Orientation: The baseline building has the exact same footprint, total floor area, floor-to-floor height, window-to-wall ratio (WWR), and compass orientation as the proposed project.
• Baseline Property Assignment: The baseline building is assigned standard local performance values for envelope thermal transmittance (U-value in $W/m^2K$), Solar Heat Gain Coefficient (SHGC), equipment efficiency (COP/EER), lighting power density ($W/m^2$), fixture flow rates, and standard construction materials.

$\text{Percentage Savings (\%)} = \left( \frac{\text{Baseline Consumption} - \text{Proposed Consumption}}{\text{Baseline Consumption}} \right) \times 100$

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The Three Resource Dimensions Detailed

1. Operational Energy

Operational energy measures the electrical and thermal energy consumed during building operation.

• Units of Measurement: Energy Use Intensity (EUI), expressed in kilowatt-hours per square meter per year ($\text{kWh}/m^2/\text{year}$).
• Evaluated Systems:
  • Building Envelope: Roof insulation, wall insulation, low-E glazing U-value, Solar Heat Gain Coefficient (SHGC), external shading devices (overhangs, fins, louvers), and Window-to-Wall Ratio (WWR).
  • HVAC Systems: Coefficient of Performance (COP) or Energy Efficiency Ratio (EER) of cooling systems, seasonal efficiency of boilers/heaters, variable speed drives (VSDs), and energy recovery ventilation (ERV).
  • Lighting & Controls: Lighting Power Density (LPD in $W/m^2$), LED efficacy, motion/occupancy sensors, daylight harvesting controls.
  • On-Site Renewables: Solar Photovoltaic (PV) arrays, solar thermal hot water systems.

2. Operational Water

Operational water measures total potable water consumed by occupants and building systems.

• Units of Measurement: Liters per person per day ($\text{L/person/day}$) or annual cubic meters ($m^3/\text{year}$).
• Evaluated Measures:
  • Sanitary Fixtures: Low-flow showerheads ($\text{L/min}$), low-flow kitchen/faucet aerators ($\text{L/min}$), dual-flush toilets ($\text{L/flush}$), waterless or ultra-low-flow urinals.
  • Water Recycling & Reuse: Greywater collection and treatment for toilet flushing and irrigation; rainwater harvesting systems.
  • HVAC Water Consumption: Evaporative cooling tower efficiency or switching from water-cooled to air-cooled chillers.

3. Embodied Energy in Materials

Embodied energy quantifies the total primary energy consumed during the cradle-to-gate lifecycle phase of building materials—including raw material extraction, processing, manufacturing, and transport to the factory gate.

• Units of Measurement: Megajoules per square meter of gross floor area ($\text{MJ}/m^2$) or embodied carbon equivalent ($\text{kg CO}_2\text{e}/m^2$).
• Evaluated Structural & Envelope Assemblies:
  • Floor slabs (e.g., solid concrete slab vs. post-tensioned slab vs. timber floor).
  • Roof construction (e.g., heavy concrete roof vs. insulated steel sheet roof).
  • External walls (e.g., solid concrete block vs. autoclaved aerated concrete [AAC] vs. hollow clay bricks).
  • Internal partitions (e.g., brick masonry vs. drywall with timber/steel studs).
  • Window frames (e.g., aluminum without thermal break vs. thermally broken aluminum vs. UPVC/timber).
  • Insulation materials.

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Step-by-Step EDGE App Interface Workflow

To perform a baseline calculation and evaluate measures, the EDGE Expert follows a systematic workflow in the EDGE App: