Adopting energy efficiency strategies in residential buildings are beneficial as these not only improve the energy performance but also improves the indoor thermal climate and minimizes the greenhouse gas emissions. There exist numerous studies on energy efficiency strategies and their influence on indoor thermal climate in residential buildings in cold climates. However, there is a lack of documented and systematic studies that explicitly investigated the selection of appropriate energy efficiency strategies and their impact on the indoor thermal climate in residential buildings in a subarctic climate. Moreover, the impact of such energy efficiency strategies on the life cycle energy use of buildings has not been given appropriate attention in the existing literature. Due to the extreme climate conditions in a subarctic climate – severe cold and dark winter with heavy snow and mild short summer – buildings require a considerable amount of heating energy to maintain a comfortable temperature indoors. Therefore, it is important to adopt energy efficiency strategies that can help obtain operational and life cycle energy savings along with a better indoor thermal climate. The aim of this study is to evaluate the impact of different energy efficiency strategies on energy use and thermal indoor climate of three selected case study residential buildings in a subarctic climate. Three research questions were formulated: (1) What is the impact of evaluated energy‐efficiency strategies on the operational energy use?, (2) What is the impact of evaluated energy‐efficiency strategies on the life‐cycle energy use?, and (3) What is the impact of evaluated energy‐efficiency strategies on the thermal indoor climate? To address research questions 1 and 3, implemented energy‐efficiency strategies in two low‐energy buildings were evaluated using measured energy data and dynamic building energy and indoor climate simulations. To address research question 2, different combinations of energy efficiency strategies were explored using a multiobjective optimization method to identify optimal retrofitting solutions in terms of life cycle energy savings for a 1980s building. Results show that besides an airtight and highly insulated building envelope, a well‐functioning heating system is important to achieve low operational energy use. Findings highlight that the role of occupants is vital both in regard to the proper functioning of the heating system and to reduce the need for active heating in an airtight and highly insulated building. The occupants are also important in terms of maintaining a comfortable indoor thermal climate, especially during summer since manual airing and shading can help moderate temperatures indoors. Furthermore, findings show that applying glazed balconies is not necessarily a favorable strategy in terms of operational energy use and indoor thermal climate for a building in a subarctic climate. In comparison, using double instead of single pane balcony glazing and lowering the window to wall ratio improved the operational energy and indoor thermal climate performance. A combination of energy efficiency strategies including the addition of insulation on walls and roofs, there placement of windows from double pane to triple pane ones and the installation of heat recovery ventilation were found optimal to achieve considerable savings in both operational and life cycle energy use. In many cases, the fundamental aim of adopting energy efficiency strategies is to reduce operational energy use, while impacts on life cycle energy use and indoor thermal climate are less prioritized. The findings illustrate the importance of considering impacts on operational energy use, life cycle energy use and indoor thermal climate simultaneously to select energy efficiency strategies that ensure a better and more sustainable built environment.

Thesis: B.S., Massachusetts Institute of Technology, Department of Building Engineering and Construction, 1949 / by Paul T. Reynolds, Richard W. Warren. / B.S. / B.S. Massachusetts Institute of Technology, Department of Building Engineering and Construction

Thesis: B.S., Massachusetts Institute of Technology, Department of Building Engineering and Construction, 1941 / Includes bibliographical references. / by Douglas Watson, Stanley H. Van Greenby. / B.S. / B.S. Massachusetts Institute of Technology, Department of Building Engineering and Construction

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No description available.

The report is a degree project in the program Construction Technology with a focus onhouses. It is about errors, changes and additional work regarding construction of smallhouses. The developer is usually a novice in the field and does not have experience inmaking decisions in the design stage. Changes and additions will then occur in varyingdegrees during the construction phase instead. This leads to unnecessary time-wasteand a higher cost. Therefore, further examination in the area is valuable to identify themost frequent change and supplementary work. This knowledge can then be used toprevent these changes from happening through purposeful planning.The methods of the survey were surveys for core stakeholders, search of archives witha review of the controller's (KA)-documentation to final consultation protocols and areview of requirement analysis through house suppliers with links to literature. Therequirement analysis with the literature review was done by contacting various housesuppliers. The house suppliers also answered questions and returned various documentssuch as quote templates.The core stakeholders who were investigated in this work include architects, builders,contractors, inspectors, control managers according to plan and the Building Act (PBL2101: 900) and house suppliers. The contractors have professions such as carpenters,excavators and project managers.The result showed both in the surveys and in the protocols (KA) that the most commonconstruction fault, changes and additions apply to installations and specificallyimplementations of various kinds. The reviews are for example pipes that go throughthe base plate or fire -rated wall.Surveys and final council protocols (KA) were analysed by being read several times.First, they were read through in order to create an overview and then in search foranswers to a specific question. Collected data was divided into different categories andcompiled. Categories are land and foundation, frame, installations, facade and ceiling,and other.The interviews with the requirement analysis as well as the documents from the housesuppliers were read through and an analysis was carried and compiled.The respondents believed that an area contained the most commonly occurring errorsand additions, but the survey and protocols (KA) showed something different. Oneinterpretation is that since an unconsciousness exists about the fact that sealing aroundimplementation is common work that has been missed, it therefore is precisely thereason why it has been missed. Number of errors with penetrations could be dependenton that there are several different contractors who need to cooperate with transitionsbetween different materials.The process between a salesperson working for house suppliers and the customer has abig impact for the occurrence of future changes or additional work.Keywords: Housing, construction failure, builder, inexperienced builder, additionalwork, changes. / Rapporten är ett examensarbete i programmet byggnadsteknik med inriktning mot hus.Den handlar om fel, ändringar och tilläggsarbeten vid byggnation av småhus.Byggherren är då vanligen en novis inom området och har inte erfarenhet av att fattabeslut i projekteringsskedet. Ändringar och tillägg kommer istället i varierande gradbehöva utföras under byggtiden. Det leder till onödigt tidsspill och en högre kostnad.Därför är det värdefullt med vidare undersökning inom området för att identifiera demest frekvent förekommande fel, ändrings- och tilläggsarbetena. Den kunskapen kansedan användas till att förebygga dessa genom en målmedveten planering.Metoderna för undersökningen var enkäter till kärnintressenter, dokumentsökning iarkiv med genomgång av kontrollansvariges (KA) underlag till slutsamrådsprotokolloch intervjuer med genomgång av behovsanalys via husleverantörer och koppling tilllitteraturen. Behovsanalysen med litteraturgenomgången utfördes genom att olikahusleverantörer kontaktades och intervjuer genomfördes. Husleverantörerna svarade påfrågor och skickade även över dokument som t.ex. offertmallar.Kärnintressenterna som undersöktes i det här arbetet inkluderar arkitekt, byggherrar,entreprenörer, inspektörer, kontrollansvariga enligt Plan och Bygglagen (PBL2101:900) och husleverantörer. Entreprenörerna har yrken såsom snickare, grävare ochprojektledare.Resultatet visade både i enkäterna och i protokollen (KA) att de vanligaste byggfelen,ändringarna och tilläggen gäller installationer och specifikt genomföringar av olikaslag. Genomföringarna kan vara rör som går genom grundplatta eller brandklassadvägg.Enkäter och protokoll (KA) analyserades genom att de lästes igenom ett flertal gånger.Först lästes de igenom i syfte att skapa en överblick och sedan i sökande efter svar påen specifik frågeställning. Data som samlades in delades upp i olika kategorier ochsammanställdes. Områden är mark och grund, stomme, installationer, fasad och taksamt övrigt.Intervjuerna med behovsanalysen samt dokumenten från husleverantörerna lästesigenom och en analys utfördes som samanställdes.Respondenterna förväntade att ett område innehöll flest förekommande fel, ändringaroch tillägg, men resultatet från enkäten och protokollen (KA) visade något annat. Entolkning är att en omedvetenhet finns kring att tätningar kring genomföringar är envanlig arbetsinsats som missats, och därav är just anledningen till att det missats.Andelen fel med genomföringar skulle kunna bero på att det är olika entreprenörer sombehöver samarbeta med övergången mellan material.Processen mellan säljaren hos husleverantören och kunden har stor betydelse förförekomsten av framtida ändringar eller tilläggsarbeten.Nyckelord: bostad, byggfel, byggherre, oerfaren byggherre, tilläggsarbeten, ändringar.

There is an important potential for a development of a building system, if the present AACblock plants are completed with high performance concrete and pre-stressing technique. This can be done as a continuation of a present AAC production or in a site factory. Hybrid cooperation between AAC and concrete is not a new technology. Traditionally, AAC is covered with rendering. The wetted material is first sprayed with cement slurry after which comes lime/cement-based rendering which strengthens the wall and supplies a mechanical protection. AAC blocks can be used as infill members in concrete deck plates and concrete framed walls (Hellers, 1993), in which the shrinkage of the surrounding concrete locks completely the cured blocks into a stable composite. A good cooperation between AAC and concrete is a requirement for the pre-stressed hybrid. This combination has been investigated with reference to bond and moisture content. The interface must have sufficient bond to supply shear strength to the structural member. Also, the concrete should be suitable for pre-stressing which requires a minimum strength class K40. Here, K60 is applied in order to reduce creep and avoid creep failure of the AAC. A production layout for the purpose is suggested. This research consists of three parts: 1- Hybrid concrete elements The principal formulation of hybrids, built on cooperation between two concrete materials, a weak AAC and a strong HPC poured on top, shows that this combination unites the most favourable qualities of the two concretes into a structural element with rational building technology. Load-bearing capacity is good, and the fire protection is excellent. Through pre-stressing of the structural concrete, a crack-free behaviour is guaranteed up to the service limit, and deflection from dead weight (incl. floor covering and possibly half the service load) be eliminated. The most important structural elements needed in a building system could be taken as hybrids. In drawings, different members like floor- roof- and wall members, window and door lintels are shown. 2- Production system for hybrids AAC blocks form a bed containing the pre-stressing steel in slits and on which high performance concrete is poured. Pre-stressing brings the two concretes together. This is especially important for the shear capacity of a building member, by which extra dowels can be omitted. The pre-stressing force is anchored by plates directly against the cured AAC blocks. A special pre-stressing bed is not required. The production is arranged in such a way that necessary equipment (trays, form strips, wedges, locks) are circulated within twenty-four hours. The necessary manpower for this facility is analysed. Normally 8 men are needed per shift. A detailed conceptual production layout for a hybrid production plant is included for discussion. See figure 6.2 (suggested production layout). 3- Application in building The hybrid members are united at joints and through seams. Continuity over connections is achieved by filling seams with mortar grout. Reinforcement may be included to achieve ductility. By a similar method, it is possible to make connections between horizontal and vertical building members. Common connection details are shown in the report. This building method replaces the equivalent method with concrete or AAC members, and it is in fact a coordination between these two. The maximum span of floor members is up to 9 m. It makes the system suitable for modern residential house production, but also suitable for office buildings, industrial halls and other applications. See attached drawings, part 2 and part 3. / QC 20101109

QC 20101118

In the design of structures to resist the effects of air blast loading or other severe dynamic loads it is vital to have large energy absorbing capabilities, and structural elements with large plastic deformation capacities are therefore desirable. Structures need to be designed for ductile response in order to prevent partial or total collapse due to locally failed elements. The research in this thesis considers experimental and theoretical studies on concrete beams of varying concrete strength. The nominal concrete compressive strength varied between 30 MPa and 200 MPa. A total of 89 beams were tested of which 49 beams were reinforced with varying amounts of tensile reinforcement. These beams were also reinforced with stirrups and steel fibres were added to a few beams. The remaining 40 beams were only reinforced with steel fibres with a fibre content of 1.0 percent by volume. Two different fibre lengths having constant length-to-diameter ratio were employed. The tests consisted of both static and air blast tests on simply supported beams. The blast tests were performed within a shock tube with a detonating explosive charge. All experimental research focused on deflection events, failure modes and loads transferred to the supports. The dynamic analyses involve single-degree-of-freedom (SDOF) modelling of the beam response and the use of iso-damage curves. Also, the dynamic support reactions were calculated and compared with test results. For beams with tensile reinforcement, the failure mode of some beam types was observed to change from a flexural failure in the static tests to a flexural shear failure in the dynamic tests. Beams with a high ratio of reinforcement and not containing steel fibres failed in shear, whereas beams with a lower ratio of reinforcement failed in flexure. The introduction of steel fibres prevented shear cracks to develop, thus increasing the shear strength of the beams. The presence of steel fibres also increased the ductility and the residual load capacity of the beams. Beams subjected to air blast loading obtained an increased load capacity when compared to the corresponding beams subjected to static loading. The SDOF analyses showed good agreement with the experimental results regardless of concrete strength and reinforcement amount. The results of using iso-damage curves indicate conservative results with larger load capacities of the beams than expected. The theoretical evaluations of the dynamic reactions were in agreement with the measured average reactions, both in amplitudes and in general shape. The experimental results with steel fibre reinforced concrete beams indicate that the dynamic strength was higher than the corresponding static strength and that the toughness was reduced when increasing the compressive strength. Beams of normal strength concrete failed by fibre pull-out while a few beams of high strength concrete partly failed by fibre ruptures. It may be favourable to use shorter fibres with smaller aspect ratios in structural elements of high strength concrete and subjected to large dynamic loads. Further research should involve studies on the size effect, on different boundary conditions, on different types of structural elements and on the combination of blast and fragment loads. The theoretical work should involve analyses both with the use of SDOF modelling and finite element analysis. / QC 20101112

Målet med detta examensarbete är att ta fram de möjliga spännvidderna vid tillämpningen av KL-trä (Korslimmat trä) som ett pelardäck. När en tvådimensionell platta läggs över pelare uppstår tryckkrafter och deformationer. Vid användningen av KL-trä som pelardäck uppstår det tryckkrafter riktade vinkelrätt mot fiberriktningen. Detta utgör ett problem eftersom denna typ av belastning är en av träets svagare hållfastheter. När pelarstommar tidigare byggts har betong varit det självklara valet. Betong erbjuder till skillnad från trä en hög tryckhållfasthet och medför även andra fördelar. En nackdel med betong är att den har ett högt klimatavtryck. Därför undersöks möjligheterna för ökad användning av klimatsmartare alternativ som trä. Genomförandet av denna uppgift sker med hjälp av handberäkningar och programvaran FEM-Design som bland annat beräknar deformationer. Resultatet visar att de maximala spännvidderna som kan uppnås med KL-träsortimentet som erbjuds idag uppgår till 5 x 7 meter. Dessa spännvidder görs möjliga tack vare en produkt s.k. Spider som hanterar de stora tryckkrafterna. / This thesis aims to determine the possible lengths between columns when a CLT (Cross Laminated Timber) is applied as a flat slab. When a two dimensional plate is supported by columns, compression and deformation occur. As the CLT is supported the compression forces are directed perpendicular to the grain. This presents a certain problem since wood’s ability to absorb this type of load is one of its weaker properties. As flat slabs previously have been built, concrete has been the obvious choice. Concrete provides high strength when exposed to compressive loads as well as bringing other advantages. One disadvantage with concrete is its great impact on the environment. Therefore, studies are trying to find more climate-smart solutions, such as wood. To establish results for this task a series of test in the software FEM-Design was used to determine the deformations. To determine the compression forces additional calculations was made by hand. The results showed that with the current assortment offered by todays CLT-manufacturers, the CLT can be supported by columns with a span of 5 x 7 m. This was made possible due to a product that was found called Spider which transforms compression forces to tensile.