Return On Investment (ROI)

Monodraught Windcatcher

Case Study Example

 

NPV ANALYSIS

Building Type

A Class 5 Office Building in Sydney, GFA 5163m2, BCA Section J DTS Specifications.

Loads

Cooling Load = 111.92kWh/m2

Heating Load = 18.14kWh/m2

 

Option 1 – Typical VAV System with HR and Outside Air Reset

Capital Cost = $180/m2

Maintenance Cost = $18/m2

Energy Cost


Cooling

-          Load = 111.92kWh/m2

-          COP = 1.73

-          Electricity = 64.69kWh/m2

-          Electricity 16c/kWh

-          Total Cost = $10.35/m2

 

Heating

-          Load = 18.14kWh/m2

-          COP = 0.75

-          Gas = 24.19kWh/m2

-          Natural Gas = 4.425c/kWh

-          Total Cost = $1.07/kWh


The total annual energy cost of Option 1 is $11.42/m2

Total annual energy & maintenance cost = $29.54/m2

 

Option 2 – Monodraught Windcatchers & Natural Gas Heaters

 

Capital Cost = $230/m2 for MD and $50/m2 for Natural Gas Heating

Maintenance Cost = $0/m2 for MD and $5/m2 for Natural Gas Heating

Energy Cost


Cooling

-          $0/m2

 

Heating

-          Load = 18.14kWh/m2

-          COP = 0.6

-          Gas = 30.23kWh/m2

-          Natural Gas = 4.425c/kWh

-          Total Cost = $1.34/m2


The total annual energy cost of Option 2 is $1.34/m2

Total annual energy & maintenance cost = $6.34/m2

 

Net Present Value of Option 2 with respect to Option 1

-          Assuming an Interest rate of 5%

-          Assuming a discount rate of 10%

  

For typical MD cost

-          NPV = 0 at approximately 5 years

-          NPV at 25 years is $233.19/m2

For MD with sales at cost price (current pricing strategy)

-          NPV = 0 at approximately 2 years