Syfte: Att undersöka effekterna vid ersättning av större delar av fasader ikontorsbyggnader med glas, där fokus ligger på energianvändning samtkoldioxidutsläpp. Metod: Kvalitativa semistrukturerade intervjuer, litteraturstudier och dokumentanalys. Resultat: En kontorsbyggnad studerades med hänsyn till den specifikaenergianvändningen och koldioxidutsläppen. Glasarean och fasadarea beräknades förden befintliga byggnaden. Sedan utökades glasarean i fasaden från 30 % till 50respektive 70 %. Resultatet visade att en ökning från 30 % till 50 % minskade denspecifika energianvändningen för samtliga fyra energiberäkningar som utfördes iGöteborg, Lund, Stockholm och Umeå. Däremot ökade den specifikaenergianvändningen för samtliga fall vid en ökning från 50 % till 70 %. Vid analyseringav koldioxidutsläppen fick man fram att koldioxidhalten alltid minskade vid ökning avglasarea. Konsekvenser: Rapporten visar tydligt att det finns ett problem gällandeenergiförbrukning och koldioxidutsläpp idag. Byggregler och råd ska följas utavbyggbranschen för att uppnå målen som EU har satt upp. Studien visar att det finns etttydligt samband mellan koldioxidutsläppen och ökningen av glasarean dock saknadesdetta samband för energianvändningen. Begränsningar: Arbetet begränsas till att undersöka en kontorsbyggnad medbetongstomme belägen i Göteborg, Stockholm, Lund och Umeå. Glasets arkitektoniskaperspektiv behandlas inte och påverkar därav inte val eller placering av glaspartier,glaset har inte några bärande egenskaper. / Purpose: To investigate the effects of replacing major parts of facades in officebuildings with glass, focusing on the energy use and the carbon dioxide emissions Method: Qualitative semi- structured interviews, literature studies and documentanalysis. Findings: An office building was studied with regard to the specific energy use andcarbon dioxide emissions. The glass area and façade area were calculated for theexisting building. Then the glass area was expanded from 30 % to 50% and 70%respectively. The result showed that an increase from 30% to 50% decreased thespecific energy use for all four energy calculations carried out in Gothenburg, Lund,Stockholm and Umeå. On the other hand, the specific energy use for all cases increasedwhen expanding the glass area from 50% to 70%. When analyzing carbon dioxideemissions, it was found that the carbon dioxide content always reduced as a result ofthe increasing glass area.Implications: The report clearly shows that there is a problem regarding energyconsumption and carbon dioxide emissions today. Building rules and advice should befollowed by the construction industry in order to achieve the goals set by the EU. Thestudy shows that there is a clear connection between carbon dioxide emissions and theincrease in the glass area, however, this connection was lacking for the energy use. Limitations: The work is limited to investigating an office building with concreteframes located in Gothenburg, Stockholm, Lund and Umeå. The architecturalperspective of the glass is not considered and therefore it does not influence theselection nor does placement of the glass portions, the glass have no bearing attributes.

Stigande byggkostnader är idag ett faktum. Materialkostnaderna för ett projekt motsvarar ungefär 45 % av den totala byggkostnaden, vilket innebär att effektivare inköp av material kan leda till stora besparingar. Som ett led i detta har byggföretagen i större utsträckning satsat på att göra internationella inköp av material från utlandet. Detta examensarbete kommer att avgränsa sig mot inköp av glasfasadelement. Skanska Sverige köper idag in glasfasader från olika glasleverantörer i Europa, med detta hoppas man kunna minska sina byggkostnader. Att köpa in material från utlandet kan även föra med sig merkostnader som minskar besparingarna som görs. Syftet med examensarbetet är att lokalisera var dessa merkostnader förekommer och ge förslag på åtgärder hur dessa kan minskas. Studierna baseras på resultatet från två av Skanskas projekt där man i ena projektet använt sig av en svensk glasleverantörer och i det andra ett utländskt. Arbetet med att lokalisera merkostnaderna har utförts genom intervjuer med nyckelpersoner inom företagen som varit delaktiga i projekten. Det som framgick ur intervjuresultaten var främst brister i projektering och montering av glasfasaderna som orsakats av kommunikationsbrist och missförstånd. Slutsatsen är att Skanska skulle möjligtvis kunna använda en enhet av projekt-koordinatorer som är delaktiga i arbetet vid projektering och montering med expertis inom internationella inköp samt utländsk arbetskraft. Detta skulle ge en bättre samordning av arbetet med de internationella inköpen och förhoppningsvis kunna minska merkostnaderna. / Increase in construction costs are now a fact. The material costs for a project is approximately 45% of the total construction cost. A more efficient purchase of materials can lead to big savings. As a part of this, the construction companies are now increasingly investing in international purchases of materials from abroad. This thesis will define itself in the purchases of curtain walls. Skanska Sweden is today purchasing curtain walls from various glass suppliers in Europe with hope to reduce their construction costs. To purchase materials from abroad may also impose additional costs that may reduce the savings. The aim of this thesis is to locate where these additional costs exists and to suggest measures on how these costs can be reduced. The studies will be based on the results from two of Skanska’s projects were one of the projects has a Swedish supplier and the other a foreign supplier of curtain walls. Efforts to locate additional costs have been done through interviews with key individuals within the companies which were involved in the projects. What emerged from the interview results were mainly shortcomings in the design and installation of the curtain walls caused by lack of communication and misunderstandings. The conclusion is that Skanska would possibly be able to use a unit of project coordinators who are involved in the work of design and installation with expertise in international purchases and foreign workers. This would provide a better coordination of the work with international purchases and hopefully be able to reduce the additional costs.

Glass has sophisticated front properties and are used as facades in high buildings. During cold periods, these glass facades could cause thermal discomfort, due to cold downdraught. Cold downdraught can be countered by placing heaters under glass surfaces. Nowadays technology offers highly insulating windows, which is why there is an interest to investigate the indoor climate with only underfloor heating. The research in this area is limited, and few empirical methods are available. Theoretical analysis has begun but it still brand new. The aim of this investigation was to present the thermal indoor climate influenced by various parameters, such as outdoor temperature, U-value and the glass height. The results were also meant to be used as reference tools in future projects. A reference building was modeled in simulation software called CFD Star-CCM+. The assignment was initiated by Incoord, a leading consulting company in energy, indoor climate and installation planning. The results showed that the air velocity increases with decreasing outdoor temperature and decreases with increasing thermal insulation (lower U-value). At the edges of the glass the air velocity becomes twice as large compared to the velocity of the air in the middle of the atrium. The air velocity (maximum and average) at 0.1 m above the floor is always higher than at 2.0 m. The lowest air velocities start from about 0.25 m/s at 0 ℃ and reaches to 0.60 m/s at -20 ℃. That means these air velocities are too high for what is accepted as a good indoor climate, where the maximum allowable air velocity is 0.15 m/s. The outdoor temperatures and the glass facade’s U-value also have an effect on the surface temperature of the glass facade. This decreases the surface temperature with decreased outdoor temperature, and the surface temperature increases at lower U-value. The height of the glass facades proved to affect both the air velocity in the occupied zone and in the glass surface temperature. The air velocity increases with the glass’ height. The increase is higher at 0.1 m than at 2.0 m above the floor. The result shows also that the average air velocity is lower than 0,15 m/s at window height lower than 5 m. But, at the same height the maximum air velocity is higher than 0.3 m/s. The surface temperature of the glass facades increases with the glass’ height. This is because the indoor heat transfer coefficient increases with height. The outdoor heat transfer coefficient is a function of the wind speed and was assumed to be constant. The underfloor heating, which is represented in the simulations with a floor surface temperature of 27 ℃, is not enough to maintain a good indoor climate in any of simulations. The results of this thesis showed a strong relation between indoor climate, outdoor temperature, U-value and the glass height. This study also showed that the floor heating is not enough to counteract the cold draft during extreme cold periods, in high glass buildings. The presented results can be used as a reference tool for the assessment of air velocities and surface temperatures, in similar high buildings.