Calculate the percentage of potable water savings for a proposed commercial toilet fixture upgrade to determine if the project qualifies for the stringent LEED Water Efficiency prerequisite.

A commercial office tower pursuing LEED certification uses whole-building energy simulation modeling. The ASHRAE 90.1 baseline building energy model estimates an annual energy cost of $500,000. The proposed building design, incorporating high-efficiency chillers, extensive daylighting controls, and a high-performance envelope, projects an annual energy cost of$325,000. Calculate the exact percentage of energy cost savings to determine how many LEED Energy & Atmosphere (EA) points the project will earn.

An architect is verifying whether a new corporate headquarters qualifies for the LEED Indoor Environmental Quality (EQ) Daylight credit using simple calculation methodologies. The total regularly occupied floor area is $1,500 \text{ } m^2$. To earn 1 point, the code requires that at least 55% of the regularly occupied floor area receives adequate daylight illumination levels between 300 Lux and 3,000 Lux on a clear day at 9:00 AM and 3:00 PM. Computer daylighting simulations confirm that exactly $950 \text{ } m^2$ of the floor plate meets these strict criteria. Determine if the project achieves the credit.

Calculate the overall U-Value of a proposed composite masonry wall assembly. The wall is composed of three solid layers: an interior 20mm Cement Plaster finish ($k=0.72 \text{ } W/m\cdot K$), a structural 150mm Concrete Hollow Block (CHB) core ($k=1.63 \text{ } W/m\cdot K$), and an exterior 50mm rigid Polystyrene Insulation board ($k=0.035 \text{ } W/m\cdot K$). Assume standard surface air film resistances of $R_{si} = 0.13 \text{ } m^2\cdot K/W$ (inside) and $R_{so} = 0.04 \text{ } m^2\cdot K/W$ (outside).

An architect is specifying high-performance windows for a high-rise residential tower in a hot climate to severely limit solar heat gain. Calculate the total thermal resistance ($R_{total}$) and the overall heat transfer coefficient (U-value) for an Insulated Glass Unit (IGU) consisting of an exterior 6mm clear glass pane ($k=1.0 \text{ } W/m\cdot K$), a central 12mm sealed argon gas cavity ($R_{argon} = 0.60 \text{ } m^2\cdot K/W$), and an interior 6mm Low-E coated glass pane ($k=1.0 \text{ } W/m\cdot K$). The surface air film resistances are $R_{si} = 0.13$ and $R_{so} = 0.04$.

A south-facing curtain wall in a tropical office building has a total area of 200 $m^2$. The peak incident solar radiation is exceptionally high at 650 $W/m^2$. Compare the instantaneous peak sensible cooling load (in kW) entering the building through the glass if the architect chooses cheap standard single-pane glass (SHGC = 0.85) versus expensive, high-performance spectrally selective Low-E glass (SHGC = 0.25).