120 likes | 245 Views
Cost optimal facade design solutions of office buildings Tallinn 10.10.2013. Martin Thalfeldt PhD student in TUT www.nzeb.ee. Objectives. Developing energy and cost efficient facade design principles for nearly zero energy building ( non-residential ) Studies so far : window U>1.0
E N D
CostoptimalfacadedesignsolutionsofofficebuildingsTallinn 10.10.2013 Martin Thalfeldt PhDstudentin TUT www.nzeb.ee
Objectives • Developingenergy and costefficientfacadedesignprinciplesfornearlyzeroenergybuilding (non-residential) • Studies so far: window U>1.0 • Questions: optimalsizeofwindows, highly transparent orsolarprotectionglazing, externalshadingornot, insulationthickness, facade vs PV • Influenced: daylight, heating, cooling, electriclighting, investment • Studyprocedures: • Energy and indoorsimulations + financialcalculationsof a genericoffice floor model • Number of windowpanesupto 5, U=0.21 • Financialfeasability-> min. 20 year NPV • Bestpossibleenergyefficiency
Methods • Criteriaformostfinanciallyfeasiblecaseisminimum net present value, whichincludesinvestmentcost and 20 yearenergyuse. • CalculationsaccordingtoEstonianenergyefficiencyrequirements Smallestenergyconsumption ≠ min €
Step 1 Minimumwindowsize • Averagedaylightfactor≥ 2% • Minimumsizedwindows
Step 2 Highly transparent orsolarprotectionglazing? Deliveredenergy Primaryenergy Highly transparent glazingallowsreachingbetterenergyefficiency!
Step3 Number ofpanes and insulationthicknessinbalance! • 3 pane glazing – insulation 200 mm (U=0,16) • 4 pane glazing – insulation 250 mm (U=0,13) • 5 pane glazing – insulation 390 mm (U=0,09)
Mostenergyefficientfacadesolution Office floor primary energy=85.5 x 1.2 = 102.6 kWh/m2 Financiallymostfeasiblesolution Office floor primary energy=93.6 x 1.2 = 112.6 kWh/m2
Coolingcapacities • Windowsizeaffectscoolingcapacitiesinadditiontoenergyconsumption • Tripleglazingwith WWR ca 25% mightbe a moresensiblesolution
FromlowenergytonZEB 3 panes, WWR 37.5% (Costoptimal) 4 panes, WWR 37.5% (North 60%) 5 panes, WWR 29.5% 5 panes, WWR 60% (Energyefficient)
Conclusion • Space heating dominatesincaseofdouble and triplewindows, theproportionof heating reducesas no ofpanesincreases • Smallerwindowsresultinbetterenergyefficiencyincaseofdouble and tripleglazing • Financiallymostfeasiblecaseistripleglazingwithhighthermalresistance (U=0.54 g=0.49), windowtowallratio ca 25%, insulationthickness 200 mm (U=0.16) • Bestenergyefficiencywasachievedwithquintupleglazing (U=0.21 g=0.24), windowtowallratio 60%, insulationthickness 390 mm (U=0.09) • Incaseofquadrupleglazing (U=0.32 g=0.36) theoptimalwindowtowallratiois ca 40% • Externalshadingisnotnecessaryifwindows are sizedaccordingtoaveragedaylightfactor 2% • Itismorereasonabletousecostoptimalfacadesolution and install more PV panels • Necessitytostudytheinfluenceofexternalshadingcontrolstrategies and doublefacade on energyefficiencyoccurred