Lecture Objectives: Show example of life-cycle cost analysis integrated in eQUEST Discuss accuracy of energy modeling Learn about moisture transport

Economic benefits Life Cycle Cost Analysis Engineering economics Energy benefits

Parameters in life cycle cost analysis Beside energy benefits expressed in $, you should consider: First cost Maintenance Operation life Change of the energy cost Interest (inflation) Taxes, Discounts, Rebates, other Government measures

Example Using eQUEST analyze the benefits (energy saving and pay back period) of installing - low-e double glazed window - economizer in the school building in NYC

Reasons for energy simulations System development Building design improvement Economic benefits (pay back period) Budget planning (fuel consumption)

System development Example: glass facade design tool THERM: heat thermal bridge analysis http://windows.lbl.gov/software/therm/7/

Therm

Detailed model Load System Plant Model Building Heating/Cooling System QBuilding QSystems eQUEST Integrated Model Building Heating/Cooling System Plant QBuilding QSystems EnergyPlus Feedback

Evaluate of the whole building simulation tools Two options: Comparison with the experimental data - monitoring - very expensive - feasible only for smaller buildings 2) Comparison with other energy simulation programs - for the same input data - system of numerical experiments - BESTEST

Source of inaccuracy when considering final results Assumptions related to the model Lack of precise input data Modeling software (tool) limitations Limitation related to available computational resources Result interpretations

How to evaluate the whole building simulation tools Two options: Comparison with the experimental data - monitoring - very expensive - feasible only for smaller buildings 2) Comparison with other energy simulation programs - for the same input data - system of numerical experiments - BESTEST

Comparison with measured data Cranfield test rooms (from Lomas et al 1994a)

BESTEST Building Energy Simulation TEST System of tests (~ 40 cases) - Each test emphasizes certain phenomena like external (internal) convection, radiation, ground contact Simple geometry Mountain climate COMPARE THE RESULTS

Example of best test comparison

Moisture transport (WUFI) http://www.wufi.de/index_e.html

Moisture transport - fundamentals However, you should be very carful how you use vapor barrier ! Theory & application (on the whiteboard)