GBCI EDGE EDGE-Expert EDGE Study Notes

In the EDGE software, the "most attractive solution" for a project, such as a hospital, is determined by balancing resource savings (energy, water, or materials) with financial payback periods, as these metrics are key outputs in the EDGE App Results Bar. The EDGE User Guide explains how to evaluate measures: "The EDGE software prioritizes measures that offer the highest resource savings with the shortest payback periods, making them the most attractive solutions for project teams. For hospitals, where energy and water demands are high due to continuous operation, measures with significant savings and faster payback are typically preferred" (EDGE User Guide, Section 2.4: Interpreting EDGE Results). Let’s evaluate the options: Option A (external shading) offers 7% savings (likely energy, as shading reduces cooling loads) with an 8-year payback. Option B (insulation of external walls) provides 3% savings (also energy) with a 9-year payback. Option C (solar hot water system) delivers 15% savings (energy, as it reduces the need for electric or gas water heating) with a 6-year payback. Option D (water-cooled chillers) achieves 20% energy savings but with a 10-year payback. The EDGE Methodology Report further clarifies: "For hospitals, measures like solar hot water systems are often attractive because they address high hot water demands (e.g., for sterilization, showers), offering substantial energy savings with relatively short payback periods due to consistent usage" (EDGE Methodology Report Version 2.0, Section 5.3: Energy Measures). Comparing the options, Option C has the second-highest savings (15%) and the shortest payback (6 years), making it more attractive than Option D (20% savings but 10 years payback), Option A (7% savings, 8 years), and Option B (3% savings, 9 years). The EDGE User Guide also notes: "A payback period of 6 years is generally considered attractive in EDGE, especially for measures with savings above 10%, as it aligns with typical investment horizons for building owners" (EDGE User Guide, Section 2.4: Interpreting EDGE Results). Additionally, for a hospital, hot water demand is significant, making solar hot water systems particularly effective: "Hospitals benefit greatly from solar hot water systems, achieving energy savings of 10-20% with payback periods often under 7 years due to high hot water usage" (EDGE Methodology Report Version 2.0, Section 4.2: Energy Savings Calculations). Thus, the solar hot water system (Option C) is the most attractive solution due to its balanced savings and shortest payback period.

Pool covers are a water and energy efficiency measure in EDGE, particularly relevant for hotels with swimming pools. The EDGE User Guide outlines their benefits: "Pool covers reduce water demand by minimizing evaporation and energy demand by reducing the need for heating, as they retain heat in the pool. In EDGE, the use of pool covers is recognized for its dual impact on reducing both water and energy consumption" (EDGE User Guide, Section 5.3: Additional Water Efficiency Measures). Option B, reduce both water and energy demand, directly aligns with this description. Option A (increase solar control and comfort) is incorrect, as pool covers are not recognized in EDGE for solar control or occupant comfort but for resource savings. Option C (require less maintenance and work from employees) and Option D (reduce chemical consumption and that of cleaning products) are potential secondary benefits but are not quantified or recognized in EDGE calculations, as confirmed by: "EDGE focuses on measurable water and energy savings from pool covers, not on maintenance or chemical use reductions" (EDGE Methodology Report Version 2.0, Section 4.3: Water Efficiency Calculations). Thus, Option B is the correct answer.

The EDGE App relies on location-specific climate data to calculate resource savings, but not all cities are listed. The EDGE User Guide provides guidance for such cases: "If the project city is not listed in the EDGE App, the user should choose the closest city to the project location that is available in the database. If necessary, the user can edit the climate data (e.g., temperature, humidity) to better reflect the project’s actual conditions, ensuring accurate calculations" (EDGE User Guide, Section 2.2: Project Setup). Option B, choose the closest city and edit the climate data if necessary, directly matches this protocol. Option A (write to EDGE Certifier and wait) is incorrect, as this is not a required step: "Users are not required to request new cities; they can proceed by selecting the closest city" (EDGE User Guide, Section 2.2: Project Setup). Option C (select any city in the same climate zone globally) is too broad and inaccurate: "Choosing a city from a different region, even in the same climate zone, may lead to incorrect assumptions about local practices and climate" (EDGE Methodology Report Version 2.0, Section 3.2: Climate Data Inputs). Option D (choose the capital city) is also incorrect unless it is the closest: "The capital city should only be selected if it is the nearest available option in the database" (EDGE User Guide, Section 2.2: Project Setup). Thus, the correct protocol is to choose the closest city and edit climate data (Option B).

In the CBCI EDGE curriculum, glazing performance is characterized using properties that directly influence solar heat gains through windows, because this is a major driver of cooling energy demand in many climates. The EDGE software uses Solar Heat Gain Coefficient, which represents the fraction of incident solar radiation that enters the building as heat through the glazing system. A lower SHGC reduces solar heat entering the indoor space, lowering cooling loads and improving the project’s energy savings in the improved case.

Shading Coefficient is an older metric that is sometimes referenced in market literature, but EDGE standardizes the glazing solar performance input using SHGC for consistency across regions and products. Solar Heat Loss Coefficient is not a standard glazing metric used in EDGE; heat loss through glazing is addressed using thermal transmittance measures such as U-value rather than an SHLC parameter. Solar Reflectivity may be relevant for certain roof or surface materials, but it is not the primary glazing property used in EDGE to quantify solar heat admitted indoors. Therefore, the correct glass property used in EDGE among the options provided is SHGC.