Low-energy doors and windows

Low-energy doors and windowsWarsaw University of TechnologyFaculty of Civil EngineeringThe Institute of Roads and BridgesMarcin Rykaczewski

WindowsHeat transfer coefficientUw the heat transfer coefficient for whole windowUw is the most important factor when we consider low-energy windows.Heat transfer coefficientUw formula:

Ag; Af glass and frame areaUg; Uf glass and frame heat transfer coefficient - linear heat transfer coefficient of thermal bridgeL length of linear bridge

Heat transfer coefficient evolutionHeat transfer coefficient requirementsRodzaj budynku, typ oknaU(max)Wymagane od 01.01. 2009Budynek mieszkalny i zamieszkania zbiorowegoOkna (z wyjtkiem poaciowych), drzwi balkonowe i powierzchnie przezroczyste nieotwieralne w pomieszczeniach o ti 16 Ca) w I, II i III strefie klimatycznej1,8 W/m2 * Kb) w IV i V strefie klimatycznej1,7 W/m2 * KOkna pomieszcze piwnicznych i poddaszy nieogrzewanych oraz wietliki nad klatkami schodowymi nieogrzewanymibez wymagaDrzwi zewntrzne wejciowe2,6 W/m2 * KHeat transfer coefficient requirementsBudynek uytecznoci publicznejOkna (z wyjtkiem poaciowych), drzwi balkonowe i powierzchnie przezroczyste nieotwieralne (fasady):a) przy ti 16 C1,8 W/m2 * Kb) przy 8 C ti 16 C2,6 W/m2 * Kc) przy ti 8 Cbez wymagaOkna i drzwi balkonowe w pomieszczeniach o szczeglnych wymaganiach higienicznych (pomieszczenia przeznaczone na stay pobyt ludzi w szpitalach, obkach i przedszkolach)1,8 W/m2 * KOkna pomieszcze piwnicznych i poddaszy nieogrzewanych oraz wietliki nad klatkami schodowymi nieogrzewanymibez wymagaHeat transfer coefficient comparisonCountryU[W/m2K]windowsAustria1,0 - 1,5Switzerland1,5Germany1,0 - 1,5Norway1,0 - 1,5Sweden1,0 - 1,5Finland1,5 - 2,0Denmark1,5 - 2,5France1,5 - 2,5Lithuania1,5 - 2,5Poland1,7 - 1,8Italy2,5 - 3,5Spain2,5 - 3,5Interesting factIn the time when the windows in our faculty were installed, the max. value of Uw=2,6W/m2K (in I,II and III climatic zone) and windows, actually, have: Uw=2,8W/m2KHeat transfer coefficientHeat transfer coefficient(Uw[W/m2K])depends on:frame [1]glazing unit (pakiet szybowy) [2]glass spacer (ramka) [3]size and shape of windowseal (uszczelka) [6]

Low-energy windows haveUw=0,85-1,00 W/m2K

U coefficient depends also on shape and size of window10Heat transfer coefficientThe bigger window we have the higher Uw value is. This follows from thefact that the glass and frame have differentvalues ofheat transfer coefficientU,in other words,largerglass surfacegiveswarmerwindow.

Glazing unitInsulated glazing (IG) double, triple or more glass windows panes separated by an air or noble gases (ex. argon) filled space to reduce heat transferacross a part of the building envelope. Panes are divided by glass spacers.U value depends on gas used, number and spacing of glass window panes.Glazing unit

Heat mirror insulating glassinner element is made of film instead of glasslower weight of window (so its size can be bigger)lower cost

Heat mirror insulating glassBecause film is essentially weightless, a second Heat Mirror film can be added for even higher insulating performance.

Heat mirror insulating glassOr even more

Glazing unitGlazing unit can be specialy prepared to avoid heat escape from inside of the building. Inner part is covered with mix of noble metals. This layer provideslightand solar energy transmission to the interior, while preventing heat transferfrom inside the house.

Glazing unit

Glazing unitOften to describe glazing unit companies put numbers like this: 4/16/44- thickness of 1st glass layer [mm]16thickness of glass spacer and at the same time the thickness of cavity filled with gas[mm]4- thickness of 2nd glass layer [mm] Windows frame materialswooden frame U=1,4 1,6 W/(m2K),PVC frameU=1,45 1,8 W/(m2K),aluminium frameinsulated profilesU=2,8 W/(m2K),non-insulated profilesU= 6,3 W/(m2K),wooden-aluminium frameWindows framethere are many types of window frames. Here are few examples:

TopThermo

PVC framethermal insulation is increased by the use of polyurethane foam inside the frame and number of empty cells inside

ELITE 92wooden frameframe is thicker, than in normal windows, to provide higher thermal resistance

ELITE 92 ALUwooden-aluminium frameframe is thicker, than in normal windows, to provide higher thermal resistancealuminium elements are used to protect window from atmospheric factors

Schco AWS 90.Si+aluminium framethermal insulation is increased by the use of foam thermal spacers and empty cells insidealuminium windows canbe much bigger than wooden,or PVC windows.

WindowsWindowwoodenPVCAluminiumAdventageseasy to repairresistant to fungi and insectsthe same as PVCecologicalweatherproofhigh strength (big dimension of window)low thermal expansionalmost no maintenance requiredideal for public buildings ( very esthetic)Disadventagesneed of regular maintenancelarge thermal expansionHigh pricehigher price than PVC framesairtight, possibility of vapour condensationHigh heat transfer coefficientsusceptible to moisturehard to repairhard or impossible to repairGlass spacerGlass spacer - element thatseparates theglassata givendistance.

Glass spacer can be made of:aluminumsteelstainless steelplastic

Glass spacerAluminium and steel have low thermal resistance so thermal bridges can occur. To avoid such situation insulated glass spacers (ciepa ramka) is used.Insulated glass spacer glass spacer made from materials with high thermal resistance ex. stainless steel, plasticExamples of insulated glass spacer

SWISSPACERframeis made ofcomposite materialwith the insulation properties, strengthened with fiberglass,coveredon one side witha thinfilmof aluminumor stainless steel.Filmprovides betteradhesionof sealantsfixingglass unit.

Assembly of windowAssembly can greatly influence thermal resistance of window. Badly mounted can create thermal bridges, contamination by moisture(zawilgocenie), fungus .Thermal insulation between window and wall must be continuous.Assembly of window

Assembly method using duo window foil

Assembly method using window tape

Assembly method using window tape

Unusual windows

Window with shutter insideWindow with shutter between glassno need of shutter cleaning (its in air tight space)

Photovoltaic windowWith photovoltaic cellsgenerates energy from sun radiation

Photovoltaic window

VERY unusual windowsWindow with bubblewrap insulation(folia bbelkowa)

DOORS

Heat transfer coefficient requirementsRodzaj budynku, typ oknaU(max)Wymagane od 01.01. 2009Budynek mieszkalny i zamieszkania zbiorowegoOkna (z wyjtkiem poaciowych), drzwi balkonowe i powierzchnie przezroczyste nieotwieralne w pomieszczeniach o ti 16 Ca) w I, II i III strefie klimatycznej1,8 W/m2 * Kb) w IV i V strefie klimatycznej1,7 W/m2 * KOkna pomieszcze piwnicznych i poddaszy nieogrzewanych oraz wietliki nad klatkami schodowymi nieogrzewanymibez wymagaDrzwi zewntrzne wejciowe2,6 W/m2 * KHeat transfer coefficient requirementsBudynek uytecznoci publicznejOkna (z wyjtkiem poaciowych), drzwi balkonowe i powierzchnie przezroczyste nieotwieralne (fasady):a) przy ti 16 C1,8 W/m2 * Kb) przy 8 C ti 16 C2,6 W/m2 * Kc) przy ti 8 Cbez wymagaOkna i drzwi balkonowe w pomieszczeniach o szczeglnych wymaganiach higienicznych (pomieszczenia przeznaczone na stay pobyt ludzi w szpitalach, obkach i przedszkolach)1,8 W/m2 * KOkna pomieszcze piwnicznych i poddaszy nieogrzewanych oraz wietliki nad klatkami schodowymi nieogrzewanymibez wymagaHeat transfer coefficientHeat transfer coefficient (U[W/m2K]) depends on:deckanditsfilling(mostly made from polyurethanefoam) [1]frame [2]seals [3]

For low-energy doors: U