# Energy Efficient System’s Savings

##### Subject

Building Services

,Climatology

,##### Academic Year

2'nd Year

,##### Complexity Level

Intermediate

,##### Content tags

Carbon Footprinting

,Energy Consumption

,Energy Efficiency

,##### Activity Type

Numerical Exercise

,##### Activity duration

< 1 hour

,##### Objective

To estimate the energy and GHG emission savings from an energy efficient air conditioner.

##### Outcome

Students will realize that energy efficiency is a great way to save energy and GHG emissions and make the design choices accordingly.

##### Requirements

None

##### Prerequisites

Conceptual knowledge of

- Electrical energy consumption
- Carbon Footprinting
- Tonnage of Operational ACs in the college

##### Given Data

- Increase in efficiency of the Air conditioning system = 10%
- Average daily operation = 8 hrs
- Average monthly operation = 22 days
- Monthly energy consumption of a typical ceiling fan ~12 kWh
- Carbon Emission Factor for Electricity = 1.19 $$\frac{\:\text{kg CO2e}}{\:\text{kWh}}$$
- 1 tree absorbs approximately 250 kg of CO
_{2}in its lifetime.

##### Procedure

** Step 1: **Students find out the total air conditioning load (TR – Ton of Refrigeration) of the campus.

** Step 2: **Convert TR to kW.

** Step 3: **Estimate the air conditioning energy consumption for a month.

** Step 4: **Select and determine energy savings for an energy efficient air conditioning system.

** Step 5: **Estimate the equivalent number of fans that can be operated due to these monthly savings.

** Step 6:** Estimate the GHG emissions saved (kg CO

_{2}e).

** Step 7:** Estimate the equivalent number of trees planted through electricity savings.

##### Sample Calculations

** Step 1:** Air conditioning load in college campus (TR) = 40 TR

** Step 2:** Air conditioning load in college campus (kW) = TR x 3.517

= 40 x 3.517

= 140.7 kW

** Step 3:** Air Conditioner’s monthly energy consumption (kWh)= Air Conditioning Load (kW) x avg. daily operation (hrs) x no. of operation days in a month

= 140.7 x 8 x 22

= 24,763 kWh

** Step 4:** Energy savings due to increase in efficiency (kWh) = % increase in energy efficiency x monthly energy consumption (kWh)

= 0.1 x 24,763

= 2,476 kWh

** Step 5:** Equivalent no. of fans that can be operated due to increased efficiency= $$\frac{\:\text{Energy savings due to increase in efficiency (kWh)}}{\:\text{Monthly energy consumption of a ceiling fan (kWh)}}$$

= $$\frac{\:\text{2476}}{\:\text{12}}$$

~206 fans

** Step 6: **GHG Emissions saved (kgCO

_{2}e) = Emission Factor for Electricity (kg CO

_{2}e/kWh) x Energy Savings (kWh)

= 1.19 x 2,476

= 2,947 kg CO_{2}e

** Step 7:** Equivalent no. of trees planted =$$\frac{\:\text{GHG Emissions saved (kg CO2e)}}{\:\text{Carbon Absorption Capacity of one tree (kg CO2e)}}$$

= $$\frac{\:\text{2946.3}}{\:\text{250}}$$

~12 trees