The present thesis has been carried out during the spring of 2017 on behalf of Gavlegårdarna AB. This is a public housing company in Gävle (Sweden) which is a large energy consumer, over 200 million SEK per year, and has the ambitious goal of reduce its energy consumption by 20 % between 2009 and 2020. Many multi-family apartment blocks were built during the "million programme" in the 60’s and 70’s when thermal comfort was the priority and not the energy saving. Nevertheless, this perspective has changed and old buildings from that time have been retrofitted lately, but there are many left still. In fact, one of these buildings will be retrofitted in the near future so a valid model is needed to study the energy saving measures to be taken. The aim of this thesis is to get through a calibration process to obtain a reliable and valid model in the building simulation program IDA ICE 4.7.1. Once this has been achieved it will be possible to carry out the building’s energy performance assessment. IDA ICE has shown some limitations in terms of thermal bridges which has accounted for almost 15 % of total transmission heat losses. For this reason, it is important to make a detailed evaluation of certain joints between elements for which heat losses are abundant. COMSOL Multiphysics® finite element software has been used to calculate these transmittances and then use them as input to IDA ICE to carry out the simulation. Through an evidence-based methodology, although with some sources of uncertainty, such as, occupants’ behaviour and air infiltration, a valid model has been obtained getting almost the same energy use for space heating than actual consumption with an error of 4% (Once the standard value of 4 kWh/m2 for the estimation of energy use in apartments' airing has been added). The following two values have been introduced to IDA ICE: household electricity and the energy required for heating the measured volume of tap water from 5 °C to 55 °C. Assuming a 16 % of heat losses in the domestic hot water circuit, which means that part of the heat coming from hot water heats up the building. This results in a lower energy supply for heating than the demanded value from IDA ICE. Main heat losses have been through transmission and infiltration or openings. Windows account 11.4 % of the building's envelope, thus the losses through the windows has supposed more than 50 % of the total transmission losses. Regarding thermal comfort, the simulation shows an average Predicted Percentage of Dissatisfied (PPD) of 12 % in the worst apartment. However, the actual value could be considerably lower since the act of airing the apartments has not been taken into account in the simulation as well as the strong sun's irradiation in summer which can be avoided by windows shading. So, it could be considered an acceptable level of discomfort. To meet the National Board of Housing Building and Planning, (Boverket) requirements for new or rehabilitated buildings, several measures should be taken to improve the average thermal transmittance and reduce the specific energy use. Among the energy saving measures it might be interesting replace the windows to 3 pane glazing, improve the ventilation system to heat recovery unit, seal the joints and intersections where thermal bridges might be or add more insulation in the building’s envelope.

The aim of this thesis is to assess the influence of superstructure implementation and thermal insulation of residential building for expenses associated with operating the property. Calculation used detached brick apartment building in Brno Slatina on the street Tilhonova 50a/50b, which has two separated entrances. The heat sources, principles of thermal insulation of residential buildings, energy prices and the possibility of her savings have been described theoretically. Various materials have been designed with different insulation thicknesses of thermal insulation material. To existing and newly designed apartment building has been processed label of the building envelope and certificate of energy performance of the building and then the values were compared. The thesis includes a calculation of the costs to perform construction modifications and determine payback period of the investment.

Reducing global energy consumption is a common challenge faced by the human race due to the energy shortage and growing energy demands. The building sector bears a large responsibility for the total energy consumption throughout the world. In particular, it was concluded that existing buildings, which are usually old and energy-inefficient, are the main reason for the high energy consumption of the building sector, in view of the low replacement rate (about 1%-3% per year) of existing buildings by new energy-efficient buildings. Therefore, improving the energy efficiency of existing buildings is a feasible and effective way to reduce energy consumption and mitigate the environmental impact of the building sector. The high energy intensity and requirements of a green building policy are the main motivation of this study, which focuses on finding cost-effective solutions to green building retrofit and maintenance planning to reduce energy consumption and ensure policy compliance. As about 50% of the total energy usage of a general building is caused by its envelope system, this study first proposes a multi-objective optimization approach for building envelope retrofit planning in Chapter 2. The purpose is to maximize the energy savings and economic benefits of an investment by improving the energy efficiency of existing buildings with the optimal retrofit plans obtained from the proposed approach. In the model formulation, important indicators for decision makers to evaluate an investment, including energy savings, net present value and the payback period, are taken into consideration. In addition, a photovoltaic (PV) power supply system is considered to reduce the energy demand of buildings because of the adequate solar resource in South Africa. The performance degradation of the PV system and corresponding maintenance cost are built into the optimization process for an accurate estimation of the energy savings and payback period of the investment so that decision makers are able to make informed decisions. The proposed model also gives decision makers a convenient way to interact with the optimization process to obtain a desired optimal retrofit plan according to their preferences over different objectives. In addition to the envelope system, the indoor systems of a general building also account for a large proportion of the total energy demand of a building. In the literature, research related to building retrofit planning methods aiming at saving energy examines either the indoor appliances or the envelope components. No study on systematic retrofit plan for the whole building, including both the envelope system and the indoor systems, has been reported so far. In addition, a systematic whole-building retrofit plan taking into account the green building policy, which in South Africa is the energy performance certificate (EPC) rating system, is urgently needed to help decision makers to ensure that the retrofit is financially beneficial and the resulting building complies with the green building policy requirements. This has not been investigated in the literature. Therefore, Chapter 4 of this thesis fills the above-mentioned gaps and presents a model that can determine an optimal retrofit plan for the whole building, considering both the envelope system and indoor systems, aiming at maximizing energy savings in the most cost-effective way and achieving a good rating from the EPC rating system to comply with the green building policy in South Africa. As reaching the best energy level from the EPC rating system for a building usually requires a high amount of investment, resulting in a long payback period, which is not attractive for decision makers in view of the vulnerable economic situation of South Africa, the proposed model treats the retrofit plan as a multi-year project, improving efficiency targets in consecutive years. That is to say, the model breaks down the once-off long-term project into smaller projects over multiple financial years with shorter payback periods. In that way, the financial concerns of the investors are alleviated. In addition, a tax incentive program to encourage energy saving investments in South Africa is considered in the optimization problem to explore the economic benefits of the retrofit projects fully. Considering both the envelope system and indoor systems, many systems and items that can be retrofitted and massive retrofit options available for them result in a large number of discrete decision variables for the optimization problem. The inherent non-linearity and multi-objective nature of the optimization problem and other factors such as the requirements of the EPC system make it difficult to solve the building retrofit problem. The complexity of the problem is further increased when the target buildings have many floors. In addition, there is a large number of parameters that need to be obtained in the building retrofit optimization problem. This requires a detailed energy audit of the buildings to be retrofitted, which is an expensive bottom-up modeling exercise. To address these challenges, two simplified methods to reduce the complexity of finding the optimal whole-building retrofit plans are proposed in Chapter 4. Lastly, an optimal maintenance planning strategy is presented in Chapter 5 to ensure the sustainability of the retrofit. It is natural that the performance of all the retrofitted items will degrade over time and consequently the energy savings achieved by the retrofit will diminish. The maintenance plan is therefore studied to restore the energy performance of the buildings after retrofit in a cost-effective way. Maintenance planning for the indoor systems is not considered in this study because it has been thoroughly investigated in the literature. In addition, a maintenance plan for the PV system involved in the retrofit of this study is investigated in Chapter 2. / Thesis (PhD)--University of Pretoria, 2017. / Electrical, Electronic and Computer Engineering / PhD / Unrestricted

This project has been carried out for the ALEC (Agence Locale de l'Energie et du Climat) of Grenoble urban area, a French energy and climate agency. It has been composed of several missions, all related to energy management in residential buildings. First, an annual energy use assessment have been conducted for two different building samples:  the eco-district of De Bonne in Grenoble and a sample of about 25 social housing buildings over the region. These two assessments showed that the average energy performance of newly built buildings is improving every year, notably under the stimulation of innovative projects such as De Bonne. Then, a more precise follow-up of construction and renovation social housing projects enabled to learn more about how to maintain energy facilities and to detect some common technical issues. The global conclusion of this project is that, although buildings are better designed today, energy performance remains fragile notably during construction and operation. To cope with that, some solutions exist and should be more systematically applied in future construction or renovation projects.

The increasing attention towards energy efficiency issues has triggered an important process involving the renovation of existing buildings and, at the same time, the creation of recognized certifications assuring the quality of the projects. In line with this trend, the Sweco headquarters, an office building characterized by 24700 m2 of floor area and located in Stockholm, was totally retrofitted in 2012 and obtained the Gold rating after being assessed with the Miljöbyggnad certification procedure. The HVAC system was a key element of the retrofit project since one of the final aims was to combine high indoor environment standards with efficient system performances. However, even if the quality of the design is certified, it is possible that, under real operating conditions, complex systems behave differently from the expectations and adjustments are necessary to correct the emerged gap. To achieve this goal, it is essential to identify the points of weakness of the system by carrying out an energy performance analysis, which is the core of this project. In fact, after providing an overview of the building and the retrofit, this work focuses on the analysis of the cooling system installed in the Sweco building and proves the importance of adopting a step-by-step approach to the problem. Therefore, an increasing level of detail characterizes each step of the analysis, whose final aim is to highlight potential aspects to be improved and create a baseline to test possible solutions. / SIRen

With an increasing awareness of energy consumption and CO 2emission in the population, several initiatives to reduce CO2emissions have been presented all around the world. The main part of these initiatives is a reduction of the energy consumption for existing buildings, while the others concern the building of eco-districts with low-energy infrastructures and even zero-energy infrastructures. In this idea of reducing the energy consumption and of developing new clean areas, this master thesis will deal with the high energy quality services for new urban districts. In the scope of this master thesis project, the new concept of sustainable cities and of clusters of buildings will be approached in order to clearly understand the future challenges that the world’s population is going to face during this century. Indeed, due to the current alarming environmental crisis, the need to reduce human impacts on the environment is growing more and more and is becoming inescapable. We will present a way to react to the current situation and to counteract it thanks to new clean technologies and to new analysis approaches, like the exergy concept. Through this report, we are going to analyze the concepts of sustainable cities and clusters of buildings as systems, and focus on their energy aspects in order to set indoor climate parameters and energy supply parameters to ensure high energy quality services supplies to high performance buildings. Thanks to the approach of the exergy concept, passive and active systems such as nocturnal ventilation or floor heating and cooling systems have been highlighted in order to realize the ‘energy saving’ opportunities that our close environment offers. This work will be summarized in a methodology that will present a way to optimize the energy use of all services aspects in a building and the environmental friendly characteristics of the energy resources mix, which will supply the buildings’ low energy demands.

About 12% of the greenhouse gas emissions and 40% of the total energy use in the EU derive from the buildings. User behavior, construction, and HVAC systems has a significant impact on a building’s energy use. If a building is to be energy-efficient it is important to understand how all these parameters are connected. This study is motivated by the need to decrease the energy use in buildings to reach the goals of energy use and greenhouse gas emissions.  In this thesis, measurements of indoor climate and electricity use, together with time diaries was used to create input data for an energy simulation model of a retirement home. A parametric study was conducted to simulate how energy demand was affected by changes in five different parameters in an office building. Also, two different energy-efficiency indicators were used to see how indicators can affect the perceived energy-efficiency of buildings. High amount of airing and low electricity use had the most impact on the heating demand in the retirement home, and electricity use had the highest impact on the total energy demand in the office building. The model of the retirement home using data gathered on-site had 24% higher energy use than the model using standard user input data. In the office building, total energy demand for heating and cooling could be lowered with 12-31% by lowering the electricity use with 30% compared to standard user input data. For office buildings the most important thing to lower total energy demand seems to be lowering the electricity use. Using today’s standard user input data does not correspond well to using on-site gathered data in a retirement home and it is therefore important to develop the standard user input data further. The indicator kWh/m2, seems to promote buildings with low occupancy. This could lead to buildings being utilized in an in-efficient way. The indicator kWh/m2 should either be replaced or combined with an indicator that takes occupancy into consideration. / Runt 12% av utsläppen av växthusgaser och 40% av den totala energianvändningen i EU kommer från byggnader. Brukarbeteende, konstruktion och HVAC-system har signifikant påverkan på en byggnads energianvändning. Om en byggnad ska bli så energieffektiv som möjligt är det viktigt att förstå hur dessa parametrar hör ihop. Denna studie motiveras av behovet att minska energianvändning i byggnader för att nå målen för energianvändning och utsläpp av växthusgaser.  I denna avhandling användes mätningar av inomhusklimat och elanvändning, tillsammans med tidsdagböcker, för att skapa indata till en energisimuleringsmodell av ett ålderdomshem. En parameterstudie genomfördes för att simulera hur energibehovet påverkades av ändringar i fem olika parametrar i en kontorsbyggnad. Två olika indikatorer för energieffektivitet användes också, för att se hur olika indikatorer påverkar hur en byggnads energieffektivitet uppfattas. Hög grad av vädring och låg elanvändning hade störst påverkan av energibehovet i ålderdomshemmet, och i kontorsbyggnaden påverkades det totala energibehovet mest av elanvändningen. Modellen av ålderdomshemmet där data insamlad på plats användes hade 24% högre värmebehov än modellen som använde standardiserade brukarindata. Det totala energibehovet för värme och kyla i kontorsbyggnaden kunde sänkas med 12-31% genom att sänka elanvändningen med 30% jämfört med standardiserad brukarindata. Det viktigaste för att få ner det totala energibehovet i kontorsbyggnader verkar vara att sänka elanvändningen. Att använda dagens standardvärden för brukarindata överensstämmer inte väl med att använda data insamlad på plats för ett ålderdomshem. Det är därför viktigt att vidareutveckla standardiserad brukarindata. Indikatorn kWh/m2 verkar främja byggnader med låg beläggning. Detta skulle kunna leda till att byggnader utnyttjas på ett ineffektivt sätt. Indikatorn kWh/m2 skulle därför behöva ersättas eller kombineras med en indikator som även tar byggnadens beläggning i beaktande.

The world is experiencing increasing energy usage owing to environmental impacts suchas climate change, Ozone layer depletion, and global warming. Energy usage is primarily categorized into transport, industrial, residential, and service sectors, with the transportation and industrial sectors taking up a considerable chunk of the energy use; Buildings partly determine the use of energy globally. This review presents a critical analysis of energy demand and uses in the building sector considering the energy optimization for The Church of Jesus Christ of Latter-day Saints in Trollhättan, including the local energy requirements. The modelling software IDA-ICE isused to conduct simulations for different scenarios. The IDA-ICE software links the actual building images with the isometric views done on a computer. The energy balance of buildings is considered with respect to the three methods for heat transfer, the U-value,ventilation, heating load, and cooling load. The study results show that the building relieson electricity and fuel for its energy supply and that fuel consumption takes the highest share, 60 %. Retrofit 1 (where the oil and electric boilers are replaced by geothermal heat pump with COP 4 for heating and domestic hot water), Retrofit 2 (which keeps changes from Retrofit_1 and where a new AHU with a VAV system replaces the existing two AHUs), and Retrofit 3 (which keeps changes from Retrofit_2 and only connects the heating system to district heating) are designed as part of the findings to understand the variation sin comfort reference, supplied Energy, used Energy, utilized Energy, auxiliary Energy, and the Energy of all zones during heating and cooling. The model results indicate that Retrofit2 demonstrates better results than the other two since it has a higher energy-saving capacity. The energy reduction for Retrofit model 1 is about 33.4 %, while Retrofit model 2 has 55% and model 3 has 33%, significantly decreasing the associated costs. The LCC analysis shows payback for the first model 6.73 years with an investment cost of 700 000 SEK, the second model has 5.84 with 1 million SEK investment, and the third model has 3.4 years with 350 000 SEK.

Energy benchmarking and disclosure policies exist in several local and state governments to manage the energy consumption of existing buildings and encourage energy efficient retrofits and upgrades, yet little is known about whether these efforts have improved overall energy efficiency. The purpose of this repeated-measures study was to examine the influence of New York City's (NYC's) Benchmarking Law (LL84) on the energy performance of the city's existing commercial buildings through investigating whether the energy performance of the city's existing commercial buildings significantly improved after the implementation of this policy. The study was based on Ostrom's institutional analysis and development framework. Paired-sample t tests were performed to statistically analyze the annually disclosed energy benchmarking data for 1,072 of NYC's existing commercial buildings that were benchmarked in both 2011 and 2016. Compared to 2011, the study results revealed statistically significant improvements in the energy performance of NYC's commercial buildings by 2016. On average, their site energy use intensity (EUI) significantly reduced by 5%, source EUI significantly decreased by 10%, greenhouse gas emissions significantly dropped by 12%, and ENERGY STAR performance rating significantly improved by 5%. However, these improvements were primarily achieved in 2012, 1 year after the city's energy benchmarking data were publicly disclosed. Additional measures should be considered to maintain continuous energy savings and greenhouse gas mitigation patterns. Positive social change implications include the potential to promote energy-efficient upgrades and inspire the adoption of sustainable building concepts.

The work deals with the impact assessment of selected parameters of residential buildings on their energy performance. Within the application of the theory of statistics database of selected residential buildings is analyzed in terms of different features that characterize it. In particular, the thermal insulating properties and individual sub-items in the energy balance are analyzed. Then the measured rate dependence of selected parameters affecting energy performance is examined using correlation and regression analysis. The results are applied in the development of computational tools for evaluating energy flows in the building.