A building owner of a small retail store wants to upgrade the $20-yr$ old HVAC system. The store

has two $10$ Ton $($or $70kW)$ rooftop units $($RTUs$)$ with an original rated full load energy efficiency

ratio $($EER$)$ of $).$ The owner is considering two options for

replacement: two standard$-$efficiency RTUs $(12$ EER$)$ with CO$2$ as refrigerant or two high

efficiency RTUs $(18$ EER$)$ with R$410$ as refrigerant. As the design energy engineer, your job is

to estimate the energy cost savings of the two replacement options compared to the existing

RTUs. You may consider the following assumptions:

Estimate annual energy costs savings for each option.

Determine simple payback period for the high efficiency RTU compared $t$ the standard$-$

efficiency with no utility incentives and with utility rebates for using high efficiency

systems of $$\frac{400}{?}$ Ton.

The cost of electricity is $$\frac{0\mathrm{.}15}{K}Wh,$ and there are no peak demand charges.

The RTUs operate at an annual equivalent of full load hours of $2200hrs.$

The installed cost of the RTUs is $$\frac{1500}{?}$ Ton for the standard$-$efficiency RTUs, and

$$\frac{3000}{?}$ Ton for the high$-$efficiency RTUs.

Reflect on how this energy$-$efficiency approach may scale to electrify the building sector

in a given location assuming thousands of similar small businesses. What maybe the

impacts on generation, demand, and global warming?