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VM Sglavo – GlassEng - UNITN 2016 VM Sglavo – GlassEng
V.M. Sglavo – GlassEng - UNITN 2016 Glass in buildings V.M. Sglavo – GlassEng - UNITN 2016 Fundamental requirements to be considered in the design activity - safety - load-bearing capacity - light transmission performances - thermal behaviour - thermal properties - acoustic insulation - fire resistance presctiptions - assemblage - maintenance norms,laws V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 Optical&thermalproperties V.M. Sglavo – GlassEng - UNITN 2016 • Glass & light • Glass & heat V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 20 Energy consumption in buildings Parte Prima Generalità V.M. Sglavo – GlassEng - UNITN 2016 Lighting power Daylighting Heating Lighting gains Solar gain Cooling Casual gains Conduction through glass Conduction through opaque Ventilation heat loss Figura 2.1. Flussi termici che interessano l’involucro edilizio 2.2. La trasmissione del calore e la trasmittanza termica Hot water 14% 2.2.1. Il caloreV.M. Sglavo – GlassEng - UNITN 2016 Quando esiste un gradiente di temperatura in un sistema o quando due sistemi a temperatura diversa vengono messi a contatto si ha trasmissione di energia. Il Electricity processo 14% attraverso il quale avviene lo scambio di energia è noto come trasmissione del calore. Di conseguenza il calore è una forma energetica di “transito” che, comparendo solo nel momento in cui in un sistema sta avendo luogo una trasformazione, non può essere misurata direttamente ma possono essere misurati MRSBULLETIN•VOLUME33•APRIL2008 gli effetti da essa prodotti (ad esempio variazione della temperatura di un corpo). Il primo principio della termodinamica afferma che l’energia non può essere né V.M. Sglavo – GlassEng - UNITN 2016 Luminous & solar characteristics V.M. Sglavo – GlassEng - UNITN 2016 lighttransmittance–Vis V.M. Sglavo – GlassEng - UNITN 2016 totalsolarenergytransmissionfactor(solarfactor)–IR UVtransmittance Glass structures, J. Wurm, Birkhäuser Verlag, 2007 V.M. Sglavo – GlassEng - UNITN 2016 !loatglass V.M. Sglavo – GlassEng - UNITN 2016 typicalvalues V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 interlayersorplasticsheets V.M. Sglavo – GlassEng - UNITN 2016 PVB – (Butacite®, SentryGlas®) PC – polycarbonate (Lexan®) UV-B 280-315nm UV-A 315-380nm blue V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 trasmittance–traslucency(surface state) V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 Glass structures, J. Wurm, Birkhäuser Verlag, 2007 V.M. Sglavo – GlassEng - UNITN 2016 Thermalproperties V.M. Sglavo – GlassEng - UNITN 2016 0.71 80-90 0.96 1.05 V.M. Sglavo – GlassEng - UNITN 2016 1.38 Wm-1K Glass science, 2nd edition, R.H. Doremus, J. Wiley and Sons, 1994 V.M. Sglavo – GlassEng - UNITN 2016 glazing V.M. Sglavo – GlassEng - UNITN 2016 d1 d2 hi Rs s in-door he V.M. Sglavo – GlassEng - UNITN 2016 out-door V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 Gasproperties V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 25 V.M. Sglavo – GlassEng - UNITN 2016 4,1+3,6=7,7 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 25 7,7 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 traditional vertical glazing - UNITN 2016 V.M. Sglavo – GlassEng d1 d2 hi=7,7W/(m2°C) Rs thermal conductivity of glass λ1 = λ2 = 1 W/(m °C) he=25W/(m2°C) 0,25 Rs(m2°C/W) s thermal resistance of the cavity (gas space) 0,2 0,15 V.M. Sglavo 0,1 – GlassEng - UNITN 2016 0 10 20 thickness(mm) V.M. Sglavo – GlassEng - UNITN 2016 −1 # 1 d1 & d 1 thermal transmittance (W/m2 °C): U = % + + R s + 2 + ( λ1 λ2016 V.M. Sglavo – GlassEng -$ hUNITN i 2 he ' −1 $1 ' dj 1 & U = + R + with>2glasses: & h ∑N si ∑M λ + h )) % i j e( N=numberofcavities M=numberofsheets € inner surface temperature: Ti = T0i − U ΔTi −e hi Example: d1 = d2 = 4 mm, s = 12 mm, T0i = 20°C, T0e=0°C € V.M. Sglavo – GlassEng - UNITN 2016 U = 2.9 W/m2 °C = 58 W/m2 if windows are 100 m2, 5.8 kW are dissipated Ti = 12.8°C V.M. Sglavo – GlassEng - UNITN 2016 Importance of inner surface temperature V.M. Sglavo – GlassEng - UNITN 2016 Mollierdiagram(psycometricorhumidair) “condensationof watervapour” V.M. Sglavo – GlassEng - UNITN 2016 Stefan-Boltzmannlaw En = εσ T 4 “thermalcomfort” emissivity(0÷1) S-Bcostant(5.67x10-8W/m2/K4) € V.M. Sglavo – GlassEng - UNITN 2016 advanced vertical glazing V.M. Sglavo – GlassEng - UNITN 2016 glass sheets coated with oxides, nitrides, metals, etc. (thickness < 1 µm) – low emissivity - & pure gas in the cavity – low conductivity - d1 d2 hi=7,7W/(m2°C) Rs s he=25W/(m2°C) V.M. Sglavo – GlassEng - UNITN 2016 Example: d1 = d2 = 4 mm, s = 12 mm, gas = argon, ε2 = 0.17 U = 1.6 W/m2 °C Ti = 16°C V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 Glass structures, J. Wurm, Birkhäuser Verlag, 2007 V.M. Sglavo – GlassEng - UNITN 2016 typicalstructures V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 cushioneffect external loads bowingeffect pressure/temperature variations V.M. Sglavo – GlassEng - UNITN 2016 Glass structures, J. Wurm, Birkhäuser Verlag, 2007 V.M. Sglavo – GlassEng - UNITN 2016 Coating technologies V.M. Sglavo – GlassEng - UNITN 2016 - spray pyrolisis - sol-gel - CVD - PVD - sputtering V.M. Sglavo – GlassEng - UNITN 2016 - on-line & off-line V.M. Sglavo – GlassEng - UNITN 2016 Spray pyrolisis V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 Sputtering V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 Coating structures V.M. Sglavo – oxide(Sn,Zn,Ti,Si,ecc.)–TiO2,Ti3N4,CrN, 4,SnO2:Sb,SnO 2:F,ZnO:Al&In2O3:Sn GlassEngZn-2SnO UNITN 2016 metal(Ag,Au,Cu,alloy) protective(SiO2) glass colour-thickness V.M. ≈500nm Au film 10 – – 20 Å - yellow Sglavo GlassEng 30 – 40 Å – orange 50 Å – purple 60 Å - blue Ag film Å – purple 2016 -15UNITN 20 Å – light blue 27 Å –blue 32 Å - green 40 Å – yellow-green V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 Coatedglasscharacteristics UVcoating(280nm-380nm) Viscoating(380nm-780nm) Solarcoating(300nm-2500nm) Thermalcoating(2500nm-25µm) V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 thermalstresses V.M. Sglavo – GlassEng - UNITN 2016 T2 T2 compression T1 tension T1 T1 < T2 - high temperature on the glass (low U) - thermal inertia of fixing and joints - heat sources next to the window V.M. Sglavo – GlassEng - UNITN 2016 - presence of elements that modify the thermal properties (labels, decorations, etc.) - presence of curtains V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 highperformanceglazings V.M. Sglavo – GlassEng - UNITNabsorbent/disperdent 2016 insulant low-emissivity solar control V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 SF=fattoresolare;LT=trasmissioneluminosa;LR=ri!lettanzaluminosa;Ug=trasmittanzatermica V.M. Sglavo – GlassEng - UNITN 2016 energy balance value UNIEN14438 EuropeanDirectiven.31/2010 D.Lgs.n.192/2005 LineeguidaMiSE2009 NormeUNITS11300 V.M. Sglavo – GlassEng - UNITN 2016 E=meanheatdispersion(heating)rate energybalance(solarheatanddispersions)foracertainperiod;usefulfor glazingcomparison,notforenergyrequirementscalculation E =U − € η gf Hp Dp V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 Trasmittanzatermica,U V.M. Sglavo – GlassEng - UNITN 2016 determinatadacalcolo(EN673)omisura(EN674,EN675) Fattorediutilità, rapporto tra l’apporto di calore utile e l’apporto di calore totale – proprietà di progetto dell’edificio; dipende dal periodo scelto e dalla sua lunghezza; per le finestre di un edificio in inverno varia tra 0.4 e 0.8 (di solito per il confronto si usa 0.6); può essere determinato per calcolo o sperimentalmente (EN 832) Fattoresolare,g determinatocomedanormaEN410 Fattoredimanutenzione,f dipendedall’accumulodisporcizia;disolitosiusa0.8 Radiazionesolareincidente,Hp quantitàdiradiazionesolarenonostruita V.M. Sglavo – GlassEng - UNITN 2016 Gradigiorno,Dp dipendonodalluogoedalperiodoconsiderato V.M. Sglavo – GlassEng - UNITN 2016 V.M. Sglavo – GlassEng - UNITN 2016 Example: U = 2.9 W/m2 °C g = 0.75 orientamento = sud h = 0.6 f = 0.8 E = 0.3 W/m2 °C V.M. Sglavo – GlassEng - UNITN 2016
