This research paper examines possible solutions for the problems that warm air heating is suffering in Nearly Zero Energy Buildings. These NZEBs are passive houses constructed to have high energy efficiency where the quantity of power used is equal to the power created annually, produced locally or in the surroundings by renewable energy sources. The problem is that this type of houses are facing problems when it comes to the heating system, where temperature of air in the ceiling is greater than on the floor, so temperature stratification happens and thermal comfort is not reached in the occupied zone. For this reason, this study is carried out and tries to find optimal solutions for warm air heating. To accomplish the investigation, an experimental study has been performed using water as the working fluid in a small-scale model. Here, paddles moved horizontally located in the center of the model at the inversion level have been used to simulate the effect that the diffuser does in the air when heating. Measurements with different paddles were made to analyze the importance of the size in the mixing and one of the paddles has been positioned on a side, next to the wall, to analyze the influence of an obstacle. It has been concluded that the area of the paddle does not have a great influence on the mixing rate, but the height of it. Also, the obstacle introduced when having the paddle next to the wall showed good results in the mixing rate. Finally, the potential energy of the water tank has not suffered any change at the surface but it has decreased at the bottom for all of the paddles, so it has been wound up that the area does not have influence on the change of potential energy. All in all, two main conclusions have been reached. On the one hand, the configuration of the air inlet diffuser significantly influences the rate of mixing. Specifically, a greater vertical size of the diffuser leads to a higher speed of mixing attainment. On the other hand, it is recommended to position the diffuser towards an obstacle, such as the adjacent wall, in order to induce turbulence. As a consequence, these findings can be investigated later in a real scale model using air as the working fluid. In this way, a solution for problems of warm air heating could be found.

This study evaluates energy performance and economic analysis of variable refrigerant flow (VRF) systems in U.S. climate locations using widelyepted whole building energy modeling software, EnergyPlus. VRF systems are known for their high energy performance and thus can improve energy efficiency in buildings. To evaluate the energy performance of a VRF system, energy simulation modeling and calibration of a VRF heat pump (HP) type system is performed using the EnergyPlus program based on measured data collected from an experimental facility at Oak Ridge National Laboratory (ORNL). In the calibration procedures, the energy simulation model is calibrated, according to the ASHRAE Guideline 14-2014, under cooling and heating seasons. After a proper calibration of the simulation model, the VRF HP system is placed in U.S. climate locations to evaluate the performance variations in different weather conditions. An office prototype building model, developed by the U.S. Department of Energy (DOE), is used with the VRF HP system in this study. This study also considers net-zero energy building (NZEB) design of VRF systems with a distributed photovoltaic (PV) system. The NZEB concept has been considered as one of the remedies to reduce electric energy usages and achieve high energy efficiency in buildings. Both the VRF HP and VRF heat recovery (HR) system types are considered in the NZEB design, and a solar PV system is utilized to enable NZEB balances in U.S. climate locations by assuming that net-metering available within the electrical grid-level. In addition, this study conducts life cycle cost analysis (LCCA) of NZEBs with VRF HP and HR systems. LCCA provides present values at a given study period, discounted payback period, and net-savings between VRF HP and HR systems in U.S. climate locations. Preliminary results indicate that the simulated VRF HP system can reasonably predict the energy performance of the actual VRF HP system and reduce between 15-45% for HVAC site energy uses when compared to a VAV system in U.S. climate locations. The VRF HR system can be used to lower building energy demand and thus achieve NZEB performance effectively in some hot and mild U.S. climate locations.

Buildings have a significant impact on energy usage and the environment. Much of the research in architectural sustainability has centered on economically advanced countries because they consume the most energy and have the most resources. However, sustainable architecture is important in developing countries, where the energy consumption of the building sector is increasing significantly. Currently, developing countries struggle with vaccine storage because vaccines are typically warehoused in old buildings that are poorly designed and wasteful of energy. This thesis created and studied a decision support tool that can be used to aid in the design of economically feasible Net Zero Energy vaccine warehouses for the developing world. The decision support tool used a simulation-optimization approach to combine an optimization technique with two simulation softwares in order to determine the cost-optimal design solution. To test its effectiveness, a new national vaccine storage facility located in Tunis, Tunisia was used. Nine building parameters were investigated to see which have the most significant effect on the annual energy usage and initial construction cost of the building. First, tests were conducted for two construction techniques, five different climates in the developing world, and three photovoltaic system prices to gain insight on the design space of the optimal solution. The results showed the difference between an economically efficient and economically inefficient Net Zero Energy building and the results were used to provide generalized climatic recommendations for all the building parameters studied. The final test showed the benefits of combining two optimization techniques, a design of experiments and a genetic algorithm, to form a two-step process to aid in the building design in the early stages and final stages of the design process. The proposed decision support tool can efficiently and effectively aid in the design of an economically feasible Net Zero Energy vaccine warehouse for the developing world.

Cette thèse développe les connaissances scientifiques sur l’origine et le comportement des polluants intérieurs en phases gazeuse et particulaire. Une description complète des processus physiques contrôlant les concentrations de polluants en air intérieur dans une pièce inoccupée et non meublée a été réalisée. En utilisant des paramètres bien quantifiés (taux de renouvellement d’air, facteur de pénétration et vitesse de dépôt), nous avons pu appliquer un modèle de bilan massique aux particules. Les résultats ont montré que, en l’absence significative de sources intérieures, une caractérisation fine des paramètres ci-dessus permettait de décrire de manière satisfaisante les concentrations intérieures en PM2.5 et PM10 à partir des données extérieures, tandis que les PM1 montrent une variabilité significativement plus marquée due aux transformations physicochimiques. Par la suite, les composés organiques volatils (COV) et la composition chimique des particules submicroniques ont été mesurés en temps réel lors d’une campagne intensive. Un enrichissement important des concentrations en COV a été observé lorsque l’air ambiant pénètre à l’intérieur du bâtiment, en particulier pour les COV oxygénés qui présentent une dépendance significative avec l’humidité relative, tandis que pour les particules les changements observés dépendent de leur composition chimique et de leur diamètre, montrant une diminution de 20% pour les PM1 à 86% pour les plus grosses particules (>5 μm). L’excès d’ammonium observé dans les deux environnements a permis de déconvoluer les nitrates organiques des inorganiques, ceux-ci présentant une dépendance plus forte avec la température, révélant une décomposition thermique plus importante en air intérieur. En résumé, l’environnement intérieur agit principalement comme une source d’émissions continues de COV, alors qu’une tendance inverse est observé pour les particules, du fait de transformations possibles pouvant se produire même dans les conditions les plus simples, sans occupant ni mobilier. / This thesis improves the scientific knowledge on the origin, behavior and fate of gas and particle-phase pollutants indoors under unoccupied unfurnished conditions. A first campaign provided a complete description of the physical processes controlling the indoor concentrations. Using well quantified parameters (air exchange rate, penetration factor and deposition rate), a mass balance model provided insights for the particle budget closure. The results showed that when indoor sources are not significant, a careful characterization of the abovementioned parameters allows to estimate PM2.5 and PM10 in a satisfying manner from outdoor data. However the PM1 fraction shows a significantly higher variability due to physicochemical transformations. Subsequently, a second intensive campaign was performed to investigate volatile organic compounds (VOC) and PM1 chemical composition in real time. A strong increase in VOC concentrations was observed when outdoor air penetrates indoors, especially oxygenated VOC which exhibited a significant dependence on relative humidity, while the changes observed for particles once indoors depend on their chemical composition and diameter, showing a decrease from 20% for submicron particles up to, 86% for large ones (>5. µm). The investigation of ammonium neutralization revealed an excess of ammonium indoors and outdoors, which is attributed to organic- in addition to inorganic-bonded ammonium nitrate. The latter showed a stronger dependency on temperature gradient from outdoors to indoors, revealing stronger thermal decomposition once indoors. In summary, the indoor environment acts mainly as a continuous emission source of VOCs, while the opposite trend is observed the particles due to possible transformations that can occur even under the simplest conditions, with no occupants and no furnishing.

Being the major energy consumer of electricity and natural gas, buildings consume more than 70% of electricity and 30% of natural gas. On the way to green buildings and zero energy buildings, investigation and improvement of energy efficiency of the buildings will result in significant reductions in energy demands and CO2 emissions / make cost savings and improve thermal comfort as well. Key steps of a successful green, energy efficient building can be summarized as whole building design, site design, building envelope design, lighting and day lighting design and HVAC system design. Energy Plus&reg / software is mainly developed to simulate the performance of the buildings in the view of the above listed points. The design of a building or the analysis of an existing building with the software will show how efficient the building is or will be, and also helps finding the best efficient choice of the whole building system. Thesis focuses on the effect of changes in building envelope properties. In Turkey, topic of green buildings has recently started to be studied. Therefore, this thesis aims to present efficient technologies providing energy savings in buildings, to present green building concept and alternative energy simulation software. In the context of this study, design, methods and material guidelines are introduced to reduce energy needs of buildings and to bring in the green building design concept. Building and system parameters to enhance building energy efficiency and energy savings together with green building principles are summarized. Moreover, whole building energy analysis methods and simulation steps are explained / year-round simulation is performed for a sample building / as a result, energy savings about 36% is achieved.

abstract: Schools all around the country are improving the performance of their buildings by adopting high performance design principles. Higher levels of energy efficiency can pave the way for K-12 Schools to achieve net zero energy (NZE) conditions, a state where the energy generated by on-site renewable sources are sufficient to meet the cumulative annual energy demands of the facility. A key capability for the proliferation of Net Zero Energy Buildings (NZEB) is the need for a design methodology that identifies the optimum mix of energy efficient design features to be incorporated into the building. The design methodology should take into account the interaction effects of various energy efficiency measures as well as their associated costs so that life cycle cost can be minimized for the entire life span of the building. This research aims at developing such a methodology for generating cost effective net zero energy solutions for school buildings. The Department of Energy (DOE) prototype primary school, meant to serve as the starting baseline, was modeled in the building energy simulation software eQUEST and made compliant with the requirement of ASHRAE 90.1-2007. Commonly used efficiency measures, for which credible initial cost and maintenance data were available, were selected as the parametric design set. An initial sensitivity analysis was conducted by using the Morris Method to rank the efficiency measures in terms of their importance and interaction strengths. A sequential search technique was adopted to search the solution space and identify combinations that lie near the Pareto-optimal front; this allowed various minimum cost design solutions to be identified corresponding to different energy savings levels. Based on the results of this study, it was found that the cost optimal combination of measures over the 30 year analysis span resulted in an annual energy cost reduction of 47%, while net zero site energy conditions were achieved by the addition of a 435 kW photovoltaic generation system that covered 73% of the roof area. The simple payback period for the additional technology required to achieve NZE conditions was calculated to be 26.3 years and carried a 37.4% premium over the initial building construction cost. The study identifies future work in how to automate this computationally conservative search technique so that it can provide practical feedback to the building designer during all stages of the design process. / Dissertation/Thesis / Masters Thesis Built Environment 2016

abstract: The building sector is responsible for consuming the largest proportional share of global material and energy resources. Some observers assert that buildings are the problem and the solution to climate change. It appears that in the United States a coherent national energy policy to encourage rapid building performance improvements is not imminent. In this environment, where many climate and ecological scientists believe we are running out of time to reverse the effects of anthropogenic climate change, a local grass-roots effort to create demonstration net zero-energy buildings (ZEB) appears necessary. This paper documents the process of designing a ZEB in a community with no existing documented ZEB precedent. The project will establish a framework for collecting design, performance, and financial data for use by architects, building scientists, and the community at large. This type of information may prove critical in order to foster a near-term local demand for net zero-energy buildings. / Dissertation/Thesis / Appendix M - Simulation and Weather Data / M.S. Built Environment 2014

Heat pumps are a vital part of each building for their role in keeping the space conditioned for the occupant. This study focuses on developing a model for the ground-source heat pump at the Zero Energy lab at the University of North Texas, and finding the minimum data required for generating the model. The literature includes many models with different approaches to determine the performance of the heat pump. Each method has its pros and cons. In this research the equation-fit method was used to generate a model based on the data collected from the field. Two experiments were conducted for the cooling mode: the first one at the beginning of the season and the second one at the peak of the season to cover all the operation conditions. The same procedure was followed for the heating mode. The models generated based on the collected data were validated against the experiment data. The error of the models was within ±10%. The study showed that the error could be reduced by 20% to 42% when using the field data to generate the model instead of the manufacturer’s catalog data. Also it was found that the minimum period to generate the cooling mode model was two days and two hours from each experiment, while for the heating mode it was four days and two hours from each experiment.

Incorporating insulation material with phase change materials (PCMs) could help enhance the insulation capability for further building energy savings by reducing the HVAC loadings. During the phase change process between the solid and liquid states, heat is being absorbed or released by PCMs depending on the surrounding temperature. This research explores the benefits of a polyurethane (PU)-PCM composite insulation material through infiltrating paraffin wax as PCM into PU open cell foam. The new PU-PCM composite provides extra shielding from the exterior hot temperatures for buildings. Through this study, it was demonstrated that PU-PCM composite insulation could potentially help building energy savings through reducing the loads on the HVAC systems based on the building energy modeling using EnergyPlus. The Zero Energy Lab (ZØE) at the University of North Texas was modeled and studied in the EnergyPlus. It is a detached building with all wall facades exposed to the ambient. It was determined that the new PU-PCM insulation material could provide 14% total energy saving per year and reduce the electricity use due to cooling only by around 30%.

I detta examensarbete studeras kommande energikrav för byggnader i Sverige och i synnerhet kraven på specifik energianvändning. Detta mot bakgrund av EU-kommissionens och EU-parlamentets direktiv, EPBD2, om nära nollenergibyggnader 2020. Därefter bearbetas ett förslag på en ny ytterväggskonstruktion som med lägre U-värde än den befintliga ytterväggen ska sänka Fiskarhedenvillans olika hustypers specifika energianvändning. Syftet med sänkningen är att möjliggöra för Fiskarhedenvillan att uppfylla de kommande energikraven. Det är många parametrar som måste uppfyllas och det nya ytterväggsförslaget analyseras förutom ur energisynpunkt även med hänsyn till statik, fukt och kostnad. Beräkningar för statik och specifik energianvändning har gjorts för ett referenshus. Resultatet av att byta ut den befintliga ytterväggskonstruktionen mot det framarbetade förslaget med ca 33 % lägre U-värde gav endast en sänkning med ca 6 % av den specifika energianvändningen. För att sänka referenshusets specifika energianvändning ytterligare bör även resterande delar av klimatskalet förbättras samt ett annat uppvärmningssätt väljas. Avslutningsvis diskuteras resultatet och vi lämnar rekommendationer för fortsatta studier. / This thesis studies future energy requirements for buildings in Sweden and in particular the requirements for specific energy use. This is in light of the European Commission and European Parliament Directive, EPBD2, on nearly-zero energy buildings 2020. A proposal for a new exterior wall construction in Fiskarhedenvillan houses with lower U-value than the existing exterior wall is analyzed. The purpose of the new wall is to reduce the specific energy use to enable Fiskarhedenvillan to meet the future energy requirements. There are many parameters that must be considered. The proposed new exterior wall construction is analyzed not only from the energy point of view but also with regard to statics, moisture and cost. Calculations for the statics and the specific energy use have been made for a reference building. The changed design of the exterior wall resulted in a reduction of the U-value with 33 % but only 6 % of the specific energy use. A further reduction of the specific energy use for the reference house requires improved design of the remaining building envelope and a new heating method. Furthermore the results are discussed and recommendations for further studies are given,