GARD developed and integrated life-cycle costing capabilities into EnergyPlus and provided both user and engineering documentation and a comparison spreadsheet. Life-cycle costing is used with building energy simulation in order to justify energy efficiency upgrades by discounting future costs based on the principal of the time value of money. The software module developed by GARD is based on discounting the future values according to normal life-cycle costing techniques as described in NIST Handbook 135 “Life-Cycle Costing Manual for the Federal Energy Management Program.” The life-cycle objects added by GARD include:
- LifeCycleCost:Parameters
- LifeCycleCost:RecurringCosts
- LifeCycleCost:NonrecurringCost
- LifeCycleCost:UsePriceEscalation
- LifeCycleCost:UseAdjustment.
The new Life-Cycle Cost Report includes tables for:
- Parameters
- Use Price Escalations
- Cash Flow for Recurring and Nonrecurring Costs (Without Escalation)
- Energy Cost Cash Flows (Without Escalation)
- Capital Cash Flow by Category (Without Escalation)
- Operating Cash Flow by Category (Without Escalation)
- Monthly Total Cash Flow (Without Escalation)
- Present Value for Recurring, Nonrecurring and Energy Costs (Before Tax)
- Present Value by Category
- Present Value by Year
- After Tax Estimate
In addition, GARD developed an EnergyPlus dataset file for use price escalations based on the most recent annual supplement to NIST Handbook 135 as well as a comparison spreadsheet that takes the results from multiple energy simulations and computes the Net Savings (NS), Savings to Investment Ratio (SIR), Adjusted Internal Rate of Return (AIRR), Discounted Payback, and Simple Payback.