The LEED AP Building Design + Construction (LEED AP BD+C) (LEED-AP-BD+C)

Minimum Energy Performance

A project’s massing and site orientation can have a direct impact on the minimum energy performance prerequisite, which requires projects to demonstrate a percentage of energy cost savings compared to a baseline building. Massing and orientation affect the amount of solar heat gain, daylight availability, natural ventilation potential, and wind exposure of the building, which in turn influence the heating, cooling, lighting, and ventilation loads and strategies. By optimizing the massing and orientation of the building, projects can reduce their energy consumption and improve their thermal and visual comfort.

This alternative analysis can help the team check the impact of reducing the amount of concrete used in the building, which can affect several impact categories, such as global warming potential (GWP), acidification, and eutrophication1. Concrete is a material with high embodied energy and carbon emissions, and reducing its use can lower the environmental impact of the building2. Optimizing the slab depth can also improve the thermal performance and daylighting of the building, which can reduce the operational energy use and demand3.

The Solar Reflectance Index (SRI) is a measure of the roof’s ability to reject solar heat, as shown by a small temperature rise. It is defined so that a standard black (reflectance 0.05, emittance 0.90) is 0 and a standard white (reflectance 0.80, emittance 0.90) is 100. SRI is calculated using the roof surface’s Solar Reflectance (SR) and Thermal Emittance (TE). SR is the fraction of solar energy that is reflected by the roof, and TE is the relative ability of the roof surface to radiate heat. Therefore, SRI includes the measure of a material’s ability to reflect solar radiation, but not its ability to absorb or emit thermal radiation.

Installing a bioretention area is an example of a low-impact development (LID) practice that can reduce runoff volume and improve water quality by replicating the natural hydrology and water balance of the site. This approach will contribute to maintaining compliance with Sustainable Sites Credit, Rainwater Management, which requires designing the site to retain the runoff from the developed site for at least the 80th percentile of rainfall events 1 . References :

Credit: Rainwater management | U.S. Green Building Council

Achieving SSc Rainwater Management in LEED v4.1

The Water Efficiency (WE) Prerequisite: Outdoor Water Use Reduction requires projects to reduce landscape water use by at least 30% over a baseline .

The baseline is calculated over the driest three-month period of the year , ensuring that water savings are measured during peak irrigation demand .

Strategies include xeriscaping, high-efficiency irrigation systems, and rainwater collection .

(Source: Official LEED BD+C Reference Manual)

The Location and Transportation Credit, Access to Quality Transit requires projects to locate within walking distance of existing or planned transit stops that provide access to quality transit service 1 .  Quality transit service is defined as transit service that meets the minimum weekday and weekend headways (time between vehicles) and hours of operation listed in Table 1 of the credit requirements 2 . According to Table 1, the minimum weekday headway for bus service is 15 minutes, and the minimum weekday headway for rail service is 10 minutes. The minimum weekend headway for both bus and rail service is 30 minutes. The minimum hours of operation for both bus and rail service are 6 a.m. to 8 p.m. on weekdays and 8 a.m. to 6 p.m.  on weekends 2 . In addition, the credit requires projects to locate within a 1/4 mi. (0.40 km) walking distance of bus, streetcar, or rideshare stops or within a 1/2 mi.  (0.80 km) walking distance of bus rapid transit stops, light or heavy rail stations, commuter rail stations, or ferry terminals 1 .

Option A does not represent quality transit service because it only has two bus lines that may not meet the minimum headway and hours of operation requirements. Option C does not represent quality transit service because it is beyond the maximum walking distance of 1/2 mi. (0.80 km) for rail stations. Option D does not represent quality transit service because it is a private shuttle bus that does not qualify as a public transportation service, and it provides hourly service that does not meet the minimum headway requirements. Option B represents quality transit service because it has a rail station that is within the maximum walking distance of 1/2 mi. (0.80 km) from the project building, and it has one train line that operates Monday through Sunday, which implies that it meets the minimum headway and hours of operation requirements.

This factor is included in the lamp lumen uplight calculation, because it represents the amount of light that is emitted downward by the fixture, which does not contribute to light pollution1. The lamp lumen uplight calculation is used to determine the percentage of total luminaire lumens emitted above horizontal, which must not exceed the maximum allowed values for each lighting zone2.

A vegetated shading structure is an example of a nonroof measure for Sustainable Sites Credit, Heat Island Reduction. The heat island effect is the phenomenon of urban areas having higher air temperatures than surrounding rural areas due to the absorption and emission of heat by human-made surfaces, such as buildings, roads, and pavements. The heat island effect can have negative impacts on the environment, human health, and energy consumption. One of the strategies to reduce the heat island effect is to use nonroof measures that provide shade, reflectivity, or evapotranspiration for at least 50% of the site hardscape, such as parking lots, walkways, plazas, and courtyards1. A vegetated shading structure is a type of nonroof measure that consists of a trellis or pergola that supports climbing plants or vines that provide shade and cooling for the underlying surface. A vegetated shading structure can also enhance the aesthetic and ecological value of the site2.

The other options are not examples of nonroof measures for Sustainable Sites Credit, Heat Island Reduction. A playground with artificial turf is not a nonroof measure, but a roof measure, as it is considered as part of the building envelope. Artificial turf is also not a compliant roof measure, as it does not meet the minimum solar reflectance index (SRI) or vegetated roof requirements1. A shade structure with a three-year aged SRI value of 0.2 is not a compliant nonroof measure, as it does not meet the minimum SRI value of 29 for nonroof surfaces1. A paving material with a three-year aged SRI value of 0.2 is also not a compliant nonroof measure, as it does not meet the minimum SRI value of 29 for nonroof surfaces1.

The LEED Platinum certification requires the project to achieve exemplary performance in at least one credit that allows it, as specified in the LEED Reference Guide 1 . One of the credits that meets this criterion is the Indoor Environmental Quality Credit, which focuses on providing healthy and comfortable indoor environments for occupants. The credit has two options: Quality Views and Enhanced Commissioning. Quality Views requires the project to have windows that provide views of natural scenery or water bodies, which can enhance the well-being and satisfaction of occupants. Enhanced Commissioning requires the project to have a comprehensive commissioning plan that ens ures all systems are properly installed, tested, and operated before occupancy. Both options can help reduce energy consumption, improve indoor air quality, and create a positive sensory experience for occupants.