NATURAL VENTILATION OF HIGH-RISE BUILDINGS - A Methodology for Planning With Different Analysis Tools and Case-Study Integration

Natural ventilation of buildings has the potential to significantly reduce energy consumption related to cooling and fanning. This can be achieved by providing good indoor air quality without any electricity demand and improving thermal comfort in the summer through increased daytime airspeed and high night ventilation rates. In high-rise buildings, however, natural ventilation is still not a widely preferred means of ventilation. The main reason is the lack of information on the required system design. Evaluation tools and instruments are not suitable for complex flow path design. Only few results are available on the performance of naturally ventilated high-rise buildings, especially where energy conservation is considered. The current thesis is predicated on this research gap. The existing barriers for implementing passive technologies can be lowered by creating a quantifiable framework that accounts for all the relevant input parameters in the design process. In order to reach this goal, a planning and simulation approach is developed. Simulations results are compared to those of a reference case-study. The 28-floor ‘Kanyon’ office tower, situated in Istanbul, is selected to demonstrate the applicability. From the energy metering, it is concluded that mechanical cooling and ventilation result in significant electricity consumption. Detailed information on the building and its operation has been made available by the building management. In addition, the impact of different moderate climates is analysed. The primary objectives of the thesis can be stated as the development of a design approach, and the investigation of the feasibility of the proposed design, based on an existing case-study building virtually adapted. The approach is developed in three steps, including conceptual design considerations, the development of a preliminary design tool, and a detailed design development. In the first step, an architectural concept is developed for wide-shaped high-rise buildings where it is impossible to realise simple cross or single-sided ventilation. Conceptual adaptations addressing the flow-path design are a central chimney strategy in respect to the building width, isolated, modular segments in respect to the building height and opposed, wind adapting openings. Other solutions proposed for passive cooling are improved shading devices and activation of the structural mass for night-time ventilation. In the second step, the originally developed ‘HighVent’ planning tool is introduced. Simple electrical circuit analogies, for both ventilation and thermal models, are found to be suitable in supporting the passive system planning. As classic design day conditions are too strict for passive system design, meaningful boundary conditions are provided. Openings can be sized automatically including an optimization process. The program first calculates the flow-path for a given airflow rate with unchanging boundary conditions. These values are then provided to the thermal module, which calculates the dynamic thermal comfort. The procedure is repeated till the system size is sufficient for passive cooling. In the third step, the annual performance is exemplarily modelled with EnergyPlus building energy simulations including airflow networks and controls. This includes the ‘HighVent’ tool preliminary design outputs, the conceptual adaptations made, and the remaining features of the as-built Kanyon building. The design approach is then further evaluated by comparing mechanical operation with an operation based on passive and hybrid control. Indicators proposed to evaluate the functionality are the energy consumption compared to that of mechanical ventilation and cooling systems, and compliance with the thermal comfort limits; additional aspects are the ventilation rates and the indoor air quality reached. Simulation results indicate that properly designed and controlled natural ventilation shows a good functionality. Control over the openings is crucial, as otherwise ventilation rates can get too high and the rooms tend to cool down too much even during summer. It is shown that the ‘Adaptive Temperature Amplifier’ control algorithm developed is very robust. Differences in climate have a varying impact. For example, in the climate of Stuttgart, further adaptations to the preliminary design are not necessary, whereas in Istanbul adaptations might be reasonable. However, to satisfy the comfort expectations in Turin, there is a necessity for adaptations or a hybrid cooling concept. That humidity values meet comfort expectations must be discussed and accepted by all project stakeholders, else hybrid operation might be a good alternative. To systematically study the possible energy conservation while maintaining thermal comfort, the energy consumption of identical buildings with different variants (passive/hybrid/active) is benchmarked against the as-built scenario. Results show that the Kanyon’s primary energy input can be reduced by approximately 30% to 40% for passive operation and by 28% to 34% for hybrid operation. This verifies the initial assumption that energy conservation of passively cooled and ventilated office spaces is significant, especially when compared to highly energy consuming state-of-the-art office towers. The results of this research work are intended, on the one hand, to support building planners in better understanding and implementing passive cooling measures and, on the other hand, to contribute to further development of sustainable building practices

Device to Perioperatively Regulate Patient Temperature for Low-resources Settings

ME450 Capstone Design and Manufacturing Experience: Fall 2015Under anesthesia, a patient's body loses its ability to regulate temperature, resulting in a core-to-peripheral redistribution of body temperature. This causes perioperative hypothermia, or hypothermia during surgery, which leads to a number of complications, such as increased risk of infection, prolonged recovery, and increased costs to both the patient and hospital. Based on many weeks of needs assessment over summer 2016, secondary public hospitals in the Dominican Republic lack methods for regulating and monitoring patient temperature during surgery, and current solutions on the market are often designed for specific use, require manual control, are not reusable, and are expensive. The prototype described in this journal consists of a underbody warming mattress placed over the operating bed to warm the patient via radiation and conduction, insulating surgical drapes to prevent radiant and convective heat loss, and a PID control system that automates temperature adjustment in response to feedback from non-invasive core body temperature measurement at the tympanic membrane and internal sensors (thermistors) as fail-safes. This project will be continued through M-HEAL, and the team plans to return to the Dominican Republic to network with new and existing stakeholders and gather user feedback on the design.http://deepblue.lib.umich.edu/bitstream/2027.42/117346/1/ME450-F15-Project06-FinalReport.pd

Design and control of mixed-mode cooling and ventilation in low-energy residential buildings in India

Energy security, climate change and economic growth are matters of critical international importance in an effort to achieve a sustainable future. Energy consumption in buildings contributes to higher greenhouse gas emissions than the industrial or transportation sectors combined. In India, the energy in the residential sector accounts for almost 50% of the total energy consumption. The need for comfortable internal environments, healthy indoor air quality and the consequences of global warming are all contributing factors to the high reliance on mechanical cooling and ventilation systems. In recent years, financial growth and increase in disposable income in India, have accelerated purchases of such mechanical systems. In metropolitan cities of India with extreme climates (hot and dry, warm and humid), the use of these systems increases by 30% every year. This upward trend is likely to continue in response to occupants’ higher comfort expectations and the continuous increase of the outside temperature during the summer months due to climate change. This could further impact the climate and the electricity grid. Innovative solutions should establish reliable strategies for cooling purposes by utilizing the use of natural ventilation. Mixed-mode buildings rely on both mechanical and natural systems to maintain comfortable conditions. Although the performance of mixed-mode buildings has already been studied and there is evidence for its positive impact on the reduction of energy demand, there is still a lack of knowledge on the best methods for controlling mixed-mode buildings. Today, the majority of the available algorithms for the control of mixed-mode systems are very simplistic and at a primitive stage of development. Typically, the control algorithms “make the decision” based on a predefined static set-point temperature, disregarding other important parameters, such as relative humidity, the position of windows and activity of occupants. Control algorithms that would account for a variety of parameters are of paramount importance to achieve energy savings whilst maintaining thermal comfort conditions. The aim of this research was to investigate the impact on thermal comfort and energy savings of novel and sophisticated control algorithms in mixed-mode residential buildings in India.Initially, it was important to identify all the control parameters that were important to be included in the control algorithms. Then the control algorithms were designed and presented in flow charts. To analyse the performance of the proposed control algorithms, computer simulations were performed, whilst a validation analysis was conducted to provide evidence of the validity of the control algorithms. Computer modelling comprised of co-simulations, using Dynamic Thermal Modelling (DTM) (EnergyPlus) and equation-based tools (Dymola using the Modelica language). The coupling of these was achieved using the Functional Mock-up Interface (FMI) for model exchange. The co-simulations enabled to examine the energy saving potential that can be achieved by the proposed control algorithms. In order to evaluate the ventilation performance of the proposed control algorithms, the ventilation rates and ventilation effectiveness of the systems were analysed using Computational Fluid Dynamics (CFD). This allowed the final analysis which included the evaluation of the ventilation performance of the control algorithms by calculating the ventilation effectiveness. To provide evidence of the proposed control algorithms and simulation approach, a validation study was done using data from an experimental chamber in India. This research has contributed to the existing body of knowledge by providing four main conclusions concerning the design and control of mixed-mode ventilation and cooling systems: i) to deliver comprehensive guidelines on the design and control of mixed-mode buildings, and the ways in which the co-simulations can be implemented to improve the existing control algorithms that can be found in the literature; ii) the use of the co-simulations showed that the developed control algorithms, when dampers/windows and ceiling fans are used, can improve the predicted hours of thermal comfort by up to 1900h compared to the scenarios when the ceiling fans were turned off, while achieving up to 55% energy reduction depending on the city; iii) the CFD simulations predicted that cross ventilation with the maximum opening areas for windows and dampers in combination with the operation of the ceiling fans can dillute the contaminants and/or heat in the building resulting in comfortable internal environments resulting in heat removal effectiveness of 1.65; and iv) the accurate and validated control algorithms that were developed in this research can be used for any study that requires control of mixed-mode buildings regardless of the geometry of the building. The use of co-simulations provides great flexibility since the same control algorithms can be used in any geometry or building location without the need for any modification of the code.</div

A Parametric Approach to Performative-based Design, Case Study: Earth Tube Ventilation

As integrated design becomes more prevalent, new workflows develop in the architectural industry. Rather than the traditional sequential pattern, the knowledge is now being applied in parallel. That is, unlike the old baton passing, the players including the architect, the engineer, the consultant, the contractor, etc. play their role simultaneously. To achieve this, an architectural ecosystem needs a compatible digital information exchange approach; an approach that involves the engineer in the strategic design of systems, increases the chances of more creative, more integrated and higher-performing systems. There are some problems in the current parametric studies such as lack of inclusivity of all building physics facets, lack of validation, and lack of proper visualization in some cases. This dissertation intends to fill in these gaps by proposing a methodology to create a performance model integrated into a popular design tool, Rhinoceros 3D, of a rather rare ventilation system, the Earth Tube Ventilation. The idea is to keep all the simulation pieces in the same place that the 3D modeling happens. The model is further validated using the data from the experiments done on the Aldo Leopold Foundation building located close to Baraboo in Wisconsin. This process can be extended to other aspects of Performative Based Design

hybridGEOTABS project : MPC for controlling the power of the ground by integration

GEOTABS is an acronym for a GEOthermal heat pump combined with a Thermally Activated Building System (TABS). GEOTABS combines the use of geothermal energy, which is an almost limitless and ubiquitous energy source, with radiant heating and cooling systems, which can provide very comfortable conditioning of the indoor space. GEOTABShybrid refers to the integration of GEOTABS with secondary heating and cooling systems and other renewable and residual energy sources (R2ES), offering a huge potential to meet heating and cooling needs in office buildings, elderly care homes, schools and multi-family buildings throughout Europe in a sustainable way. Through the use of Model Predictive Control (MPC), a new control-integrated building design procedure and a readily applicable commercial system solution in GEOTABShybrid, the overall efficiency of heating and cooling will be significantly improved in comparison to current best practice GEOTABS systems and its competitiveness will be strengthened. The present paper is the first of a series that first introduces the hybridGEOTABS project and then specifically focuses on the control-related aspects of the hybridGEOTABS solution, the MPC, providing some interesting insights of its potential development

Outdoor test cells for building envelope experimental characterisation - A literature review

partially_open4siThe present work has been partially developed within the framework of IEA EBC Annex 58In the past decades the construction sector experienced the diffusion of a wide variety of complex building envelope components and passive elements and strategies, characterized by a dynamic response to the climatic parameters. Many of these components have been claimed to contribute to reducing building energy use and improving occupants’ comfort. These kind of envelope elements need nevertheless to be tested under laboratory and real dynamic weather conditions in order to characterise, and possibly to model, their behaviour and their effectiveness both in terms of energy saving and indoor environmental quality. Both indoor laboratories and outdoor test cells have been developed in order to tackle the challenging issue of experimentally characterising innovative envelope elements. However, not always the experimental methodologies are fully and explicitly described in the available literature, and they are rarely compared to other types of experimental procedures. The aim of the present paper is to describe and review recent state of the art technologies for outdoor test cells. The paper starts with a short introduction on potentialities and limitations of outdoor facilities with respect to indoor laboratories and real buildings field tests, and it continues with a detailed classification and description of the most relevant outdoor test cells developed in recent years.openCattarin, Giulio; Causone, Francesco; Kindinis, Andrea; Pagliano, LorenzoCattarin, Giulio; Causone, Francesco; Kindinis, Andrea; Pagliano, Lorenz

Tilalämmityksen kysyntäjousto mallipohjaisella algoritmilla toimistorakennuksessa

Decreasing the CO2 emissions of building stock plays a remarkable role in the mitigation of global warming. The share of building sector from both the global final energy use and CO2 emissions is about 30%. Demand response of electricity and district heating provides one tool for decreasing emissions in the whole energy system. In demand response the buildings energy use is controlled so that the peak-load consumption in the energy grid decreases and the consumption profile stabilizes. CO2 emissions are reduced since the need for emission-intensive peak-demand generation decreases. The building owners benefit from the energy cost savings and the energy producers from the higher grid efficiency and decreased investments for peak-demand power plants. The main objective of this thesis was to define the potential of space heating demand response in the perspective of local thermal comfort, cost savings and energy flexibility. Demand response was implemented using a model predictive control algorithm (MPC) that optimized and controlled the space heating temperature setpoints. The MPC algorithm was tested with dynamical simulation model of an educational office building located in Aalto University campus area. The second research question was to examine how the demand response of space heating affects the local thermal comfort of occupants. The draught risk during the demand response was investigated by thermal manikin measurements in workstations near windows. To prevent the draught risk, a window surface temperature restriction was implemented in the MPC control algorithm and its influence on the demand response potential was investigated with different properties of windows. The thermal comfort measurements showed that the draught risk increased in workstations adjacent to windows during the decreased heating power. The increase in draught risk was noticed when the window surface temperature dropped below 15 °C while the heating was turned OFF. The influence from the window surface temperature restriction on the demand response potential was found to be small. With energy efficient windows, the influence was negligible and with non-energy efficient windows the demand response potential was affected only when unnecessary high power requirements were set. Using the MPC algorithm, the annual heating cost of the case building could be decreased 4.7%. The highest energy flexibility obtained was 14%.Rakennusten hiilidioksidipäästöjen vähentämisellä voidaan edistää merkittävästi ilmastonmuutoksen torjumista, sillä rakennusten osuus kokonaisenergiankulutuksesta (ja hiilidioksidipäästöistä) maailmassa on noin 30%. Sähkön ja lämmön kysyntäjousto rakennuksissa on yksi keino koko energiajärjestelmän kasvihuonepäästöjen vähentämiseen. Kysyntäjoustossa kuluttajat muuttavat kulutustaan siten, että energiaverkon huipputehon tarve laskee ja kulutuksesta tulee stabiilimpaa. Kysyntäjousto vähentää kasvihuonepäästöjä, sillä energia- ja päästöintensiivisiä huippuvoimalaitosten käyttötarve vähenee. Kysyntäjoustosta on hyötyä rakennusten omistajille kustannussäästöjen muodossa ja energiayhtiöille investointitarpeen pienenemisenä sekä verkon hyötysuhteen paranemisena. Tämän tutkimuksen tavoitteena oli tutkia tilojen lämmityksen kysyntäjoustopotentiaalia kustannussäästöjen, energiankäytön joustavuuden ja lämpöviihtyvyyden näkökulmasta. Lämmityksen kysyntäjousto toteutettiin tilojen lämmitystä ohjaavan mallipohjaisen algoritmin avulla. Algoritmia testattiin Aalto yliopiston kampusalueella sijaitsevaan opetusrakennukseen dynaamisen simulointityökalun avulla. Toisena tutkimuskysymyksenä oli selvittää millainen vaikutus lämmityksen kysyntäjoustolla on lokaaliin lämpöviihtyvyyteen. Tässä työssä kysyntäjouston vaikutusta vetoriskiin tutkittiin kokeellisesti lämpönuken avulla työpisteissä, jotka sijaitsivat ikkunoiden lähellä. Kylmistä ikkunapinnoista johtuvan vetoriskin välttämiseksi kysyntäjoustolle asetettiin rajoite mallipohjaisessa algoritmissa, jonka vaikutusta kysyntäjoustopotentiaaliin tutkittiin erilaisilla ikkunoiden ominaisuuksilla. Kokeelliset lämpöviihtyvyysmittaukset osoittivat, että vetoriski ikkunoiden lähellä sijaitsevissa toimistopisteissä kasvaa, kun pattereiden tehoa lasketaan kysyntäjouston aikana. Vetoriskin huomattiin kasvavan, mikäli ikkunan pintalämpötila laski alle 15 °C, kun patterit eivät olleet päällä. Vetoriskin pienentämiseksi tehdyn rajoitteen vaikutus kysyntäjoustolla saavutettaviin kustannussäästöihin sekä energiajoustavuuteen huomattiin olevan pieni. Energiatehokkailla ikkunoilla vaikutus kysyntäjoustopotentiaaliin oli mitätön, ja huonoilla (U-arvo = 2,6 W/m2K) ikkunoilla potentiaali laski vasta tarpeettoman suurilla lämmitystehon korotuksilla. Mallipohjaisen algoritmin avulla tutkitun toimistorakennuksen vuotuisia lämmityskustannuksia pystyttiin vähentämään noin 4.7%. lämmityksen joustavuudeksi saatiin parhaassa tapauksessa 14%

Semi-Open Space and Micro-Environmental Control for Improving Thermal Comfort, Indoor Air Quality, and Building Energy Efficiency

Local air delivery, heating, and cooling combined with local space partition and confinement (called semi-open space or SOS) have the potential to provide micro-environment that is tailored to the individual preference of the occupants, and hence increase the percentage of satisfied occupancy from currently 80% to near 100%. This research investigates the use of a micro-environmental control system (µX) and semi-open space (SOS) to efficiently provide the desired thermal comfort and air quality conditions for individual occupants while the ambient air temperature set-points were relaxed for reducing the overall energy consumption of the building. A computational fluid dynamics (CFD) model was developed and validated. The model in combination with the results from full-scale chamber experiments was used to evaluate the performance of proposed cooling/heating delivery system and the role of the SOS. During summer time, a cooler air was supplied locally. It was found that the cooling performance increased more by increasing the supply air flow rate than reducing the supply air temperature when the total cooling power is constant, and the cooling performance of the Air Terminal Devices (ATDs) was highly dependent on the shooting angle. The cooling efficiency increased dramatically with the supply air temperature. Also, both the CFD model simulation and experimental work has demonstrated that the heat loss by the manikin was sensitive to the distance between the diffuser and the manikin. However, this effect was also related to the clothing material on the manikin. During the winter time, the idea of heating a person with only a warm air jet was shown to be not efficient, but the confinement box was able to improve the heating performance by two to three times. A more ergonomically-friendly warming foot mat with a reflective box was very effective to restore people’s thermal comfort when the ambient space air was maintained at a lower temperature set-point for energy saving. The existence of the cubicle, as an SOS, significantly changed the airflow pattern in the office, and hence the thermal environment and air quality distribution. The cubicle could “protect” the occupants from the background air flow by reducing the average velocity as well as increasing the average temperature in the occupied space. The openness of the cubicle weakened the “protection” of the cubicle depending on the opening’s orientation and size. The “protection” may not be favored regarding thermal comfort and air quality when the emission is inside the cubicle, but it should be encouraged when the emission is outside the cubicle. The combination of the µX with the SOS can create an independent micro-environment regarding thermal comfort and air quality as well as maintain the privacy of the occupant. As a secondary goal, the ability of the CFD model to adequately predict the local heat transfer from the human body and its limitation were also investigated. The case without the µX compared better with the experiment than the case with the µX from the heat transfer point of view. The effect of the clothing material could be properly represented by a constant temperature difference or as a layer of thermal resistance. Moreover, it was found the fidelity of the surface temperature control for the manikin affected the validation of the CFD model. The concept of SOS was defined for the first time in this study and SOS’s role in shaping the microenvironment with and without local heat, cooling and ventilation were investigated both numerically and experimentally. The detailed CFD model developed has accurate representation of the effects of the manikin’s geometry and the effect of clothing thermal resistance on the boundary conditions for the CFD simulation, which can be used for the investigation of effects of air velocity, temperature, room air flow pattern and clothing on the local and overall average heat loss from human bodies and the resulting thermal comfort of the building occupants under various internal room and partition configurations

Thermal Performance of Case-study Apartment Buildings in Temperate Climate Zones in Australia: Measurements, Modelling, and Codes

Population growth and lifestyle incentives have led to an increase in the amount and proportion of people living in apartment dwellings in Australia’s capital and major regional cities. Concurrently, there have been ongoing increases in energy efficiency regulations for residential buildings in Australia in efforts to reduce greenhouse gas emissions generated through energy used for space conditioning to maintain thermal comfort. However, there is uncertainty as to whether the intended benefits of these energy efficiency regulations are being realised due to uncertainties in the simulation-based compliance process. This issue is particularly significant for apartments as there is very little quantitative evidence of the thermal performance of Australian apartments, despite the introduction of energy efficiency regulations in 2005 and the significant apartment development boom that has occurred since then. The underlying operating mechanism of these regulations is to enforce improvements to thermal performance of the building envelope. While regulations have increased the amount of insulation installed in dwellings, the estimated performance benefits may be overstated as, at the time of writing, thermal bridging effects are not considered in residential buildings. The aims of this study were therefore to understand and quantify the thermal performance of a set of case-study apartments in Australia, and to compare this measured thermal performance to that simulated using the Nationwide House Energy Rating Scheme (NatHERS) mandated building performance simulation (BPS) software and protocol of assumptions. The study also aimed to assess the impact of uncertainties associated with assumptions in the NatHERS protocol regarding thermal conditions, occupant behaviour, weather conditions, and building envelope performance. Finally, the study sought to quantify the impact of thermal bridging in apartments