CASE30 · Buildings · Retrofit modeling and LCC
Evaluating what to retain, repair or replace before a major building retrofit
Condition assessment and a DOE-2.1E baseline model support retrofit alternatives for the envelope, lighting, HVAC and plant. Life-cycle cost links initial investment to annual energy cost.
01 · CASE ANALYSIS
Start with existing equipment condition
The first decision was which assets could remain in service, which required repair and which justified replacement. Efficiency alone did not describe leakage, corrosion, insulation or control condition.
A site checklist organized envelope, air conditioning, heating, cooling, hot-water and electrical-system inspection.
02 · CASE ANALYSIS
Baseline modeling method
Collect drawings, weather, envelope properties, equipment specifications, schedules, utility use and tariffs. Convert the existing building into a DOE-2.1E energy model.
Review verification reports and suspicious inputs before running alternatives. A baseline built from incorrect schedules or equipment assumptions cannot support reliable investment comparisons.
| System | Inspection focus |
|---|---|
| Envelope | Infiltration and wall/window/roof insulation |
| Air systems | Temperature/pressure control, coils, leakage, dampers and valves |
| Heating | Boiler/pump performance, steam/condensate leaks and heat exchangers |
| Cooling | Chillers, pumps, towers, insulation and corrosion |
| Hot water | Tanks, pumps, piping and thermal losses |
| Electrical | Transformers, panels and cables |
03 · CASE ANALYSIS
Alternative design questions
Compare insulation, glazing, window location and area, lighting density, daylighting, transformer sizing and variable-speed/high-efficiency technologies.
For mechanical systems, compare zoning, plant capacity and unit count, HVAC type, chiller/boiler/pump specifications, thermal storage and solar-thermal alternatives.
04 · CASE ANALYSIS
Life-cycle investment assessment
Evaluate construction cost and annual energy cost together. A large modeled energy reduction does not necessarily produce the most favorable retrofit investment.
The source describes a consulting and decision framework; it does not provide a confirmed project-wide savings percentage or completed investment outcome.
| Alternative family | Decision basis |
|---|---|
| Envelope and lighting | Function, installation cost and annual energy cost |
| HVAC zoning and system type | Room use, comfort and life-cycle cost |
| Plant capacity and staging | Annual/peak loads and part-load operation |
| Thermal storage and solar thermal | Investment, usable output and annual cost |
05 · CASE ANALYSIS
Verification after implementation
Retain the assumptions and selected alternative as the design record. Compare actual post-retrofit utilities with a baseline adjusted for weather, occupancy and operating changes.
The practical value is a defensible sequence from physical condition through model quality to investment choice.
APPLY TO YOUR SITE
Connect your operating data to an actionable energy strategy.
Discuss the measurement boundary, data quality, operating constraints and verification approach for your facility.
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