Reducing the performance gap using calibrated simulation models

Buildings have a significant impact on the environment. Construction of buildings and their operation accounts for 36% of global final energy use and 40% of energy‐related carbon dioxide (CO2) emissions. Also, as per the 2019 International Energy Agency (IEA) and United Nations Environment Programme (UNEP) report, the building sector has a strong potential to provide long-term energy and greenhouse gas emission savings without high financial costs. Building performance simulation tools, ranging from steady-state calculations to dynamic simulation methods, can calculate the anticipated energy consumption of a building with adequate levels of accuracy. However, there is considerable evidence to suggest that buildings underperform post-completion when compared against the expected performance prediction during the design-stage. The difference between the actual operation and the design intent is termed the ‘performance gap’. While the energy performance gap in buildings is a well-known phenomenon, its in-use interpretation is quite vague. It is important to understand the basis of assumptions and protocols used in design-stage performance calculations to assess the causes of the performance gap. In the context of the performance gap, energy performance is generally the most emphasised. The gap, however, is not limited to energy – it also applies to indoor environmental quality (IEQ) parameters, such as temperature and air quality. Moreover, the pursuit of energy efficiency may have the unintended consequence of compromising IEQ, thereby requiring a comprehensive approach to performance assessment. It is therefore important to consider energy and IEQ performance issues together. This thesis contributes to an improved understanding, quantification and resolution of performance gap related issues by using a novel simulation-based approach that enables systematic identification and classification of the root causes of the performance gap. A new measurement and verification (M&V) framework that is underpinned by building performance simulation and calibration is proposed. A key aspect of this new methodological framework is the identification and separation of the three types of performance gaps because of: 1. Use of inappropriate design-stage calculation methods (such as those used for regulatory compliance), 2. Technical issues with the building, its systems and their operations, and 3. Operational changes that the building has gone through to meet its functional requirements. For the first type of performance gap, CIBSE TM54 (CIBSE, 2013a) already provides guidance to reduce the perceived gap and enable improved estimates of building performance during the design-stage. This thesis focuses on the understanding of operational-stage issues and their detailed causes, related to the second and third types of the performance gap. This thesis is the first study that systematically defines, identifies and separates, • the technical issues that cause the performance gap between design intent and actual operation, and • the deviations of operating conditions from the design that are driven by the building’s function and occupancy. This is achieved by integrating the conventional post-occupancy performance assessment approach with building performance modelling and evidence-based model calibration. Another addition to the conventional approach, explored in this study, is the incorporation of IEQ. The issue of IEQ is addressed in two ways: first, by using zonal temperatures for calibration cross-validation, and second, by assessing the energy-related unintended consequences of IEQ underperformance which may happen during building operations. The calibrated simulation models are operationally accurate virtual representation of the actual building and can help to isolate the performance issues and validate the findings. The new framework proposed in this thesis is better suited than conventional M&V protocols such as ASHRAE (American Society of Heating Refrigerating and Air Conditioning Engineers) Guideline 14 and IPMVP (International Performance Measurement and Verification Protocol). These conventional M&V protocols also propose a calibration-based approach, but they generally focus on broad statistical requirements and are not tied to a framework for a procedural verification of all the most important issues that can cause the performance gap. It is likely that using these conventional protocols will identify some key issues during investigations while leaving other potential issues hidden. The guidance on calibration and validation provided in conventional M&V protocols is commonly used for all model calibration exercises. However, the conventional protocols were developed for calculating energy savings in retrofit applications, and the calibration criteria defined in them are mainly for checking the accuracy of building-level energy use totals. The calibration criteria do not check for the uncertainty or the accuracy of dependent parameters, such as zone temperatures and other environmental outputs, which could cross-validate the model. Mathematically, meeting just the statistical criteria for building-level energy use totals in a highly parameterized model and an under-determined search space can lead to unrealistic solutions also being validated. To better support the calibration accuracy with the new proposed M&V framework, advanced model validation criteria have also been developed. New multi-level calibration criteria are proposed, which factors in data quantity, quality and granularity. In this new advanced validation criteria, the current industry standard of monthly energy use checks is the lowest level of calibration, with higher levels requiring detailed checks, using granular and disaggregated energy use. However, all levels of calibration require minimum dependent parameter checks, such as IEQ checks for typical zone temperatures. Dependent parameter checks are desirable in model calibration; however, current statistical criteria used for calibration are not suitable for these checks. Revised and new metrics and thresholds are proposed and explored in this thesis for use in advanced calibrated model validation checks. Beyond the use of IEQ parameters (e.g. zone temperatures) in model calibration, another area of focus of this thesis is the unintended IEQ underperformance captured during the monitoring. The scope of this assessment is limited to underperformance in IEQ parameters linked to achieving high energy efficiency objectives, thermal comfort and indoor air quality (IAQ). Amongst the various IEQ parameters, thermal comfort and IAQ have complex and dynamic interactions with buildings energy end-uses. Comprising of multiple factors, which are both subjective and empirical, thermal comfort and IAQ performances have a high interrelation with the energy performance objectives. Therefore, along with conventionally tracked parameters of temperature and CO2, additional IAQ parameters (not used during the calibration process), such as NO2, PM2.5 and PM10, are analysed to enhance the understanding of unintended energy-related IEQ underperformance. The new methodology proposed in this study is applied to five case study buildings across four building sectors – offices, schools, hospitals and apartment blocks. These buildings represent a large cross-section of the UK building stock and, therefore, can provide useful insights into the issues in the construction sector that drive the performance gap. While detailed performance assessment and advanced validation is done for all five case study buildings using the proposed framework, in one case study building the multi-level calibration checking criteria is also fully explored. Using this methodology on the various case study buildings, cross-sectoral lessons, related to root causes of the energy performance gap and applicable in the wider industry context, are uncovered. Linking to the three types of performance gaps mentioned earlier, analysis of the results shows that, in most of the case studies, some of the energy performance gap is the perceived gap (related to point 1: use of inappropriate design-stage calculation methods) or is because of operational changes (related to point 3: changes that the building has gone through to meet its functional requirements). However, the most critical cause of the gap is due to technical issues (related to point 2: issues with the building, its systems and their operations) identified across the case studies. These issues were either design errors, improper construction and installation, poor commissioning or shortcomings in building systems and the use of new low-carbon technologies. It was observed that long-term involvement (with responsibility for the operational performance) of the design and construction teams are effective in lowering performance gaps. Issues related to IEQ were also observed across the case studies, such as overheating risks and poor IAQ. These added to the existing knowledge of energy-related IEQ issues and highlighted the need to address IEQ simultaneously with energy through better design, advanced operational controls and by incorporating regular IEQ measurements as part of operations and maintenance protocols. The novel approach presented here builds a case to move building performance calculations towards an operational context, where design projections are done using advanced simulation and with a view of tracking the projections through to operation using measurable performance outcomes. Overall, the study shows the importance of the early involvement of all stakeholders and their accountability to minimise performance issues. Integrating the findings from the case studies, a case could be built for having IEQ performance objectives in energy performance contracts. This can mitigate the trade-offs of IEQ against energy performance that leads to unintended health consequences for occupants. Further, this work promotes a way of integrating dynamic thermal simulation in regular post-occupancy checking and management of buildings

Collective Action Dynamics in Urban Neighborhoods: A Study of Urban Community Gardens

Lessons from various policies and programs both in the United States and international development have led to a knowledge base concluding that an engaged community is a critical component for developing a thriving community. This is based on a premise that even in the modernized world community still has a role to play along with government and the market in their own development. Community’s role is further highlighted in areas such as low-income urban neighborhoods where both the government and the market may not be able to fulfill all the needs. Research has followed by trying to understand why people engage in community activities. Studies have highlighted various individual and organizational attributes that motivate people to engage. Most studies take a linear view and don’t take into account how the dynamics of internal processes and external environment may affect motivation over time. Without a dynamic perspective, it is difficult to understand what sustains community engagement. Not only engagement but sustained engagement is critical to accrue benefits for both individual and the community. This study is designed to shed light into that very question: what are the processes that lead to sustained or eroding engagement over time? The study was conducted in the empirical context of community gardens in a low-income urban neighborhood. Key informant interviews were conducted with gardeners from different community gardens in the neighborhood. The data was used to understand the context for the establishment of the gardens. The data was also used to revise a system dynamics model that was previously built based on theories of collective action, community garden literature, and other models. The system dynamics approach entails creating a structure of feedback loops, creating a computer model based on that structure, and analyzing the simulation results to understand the relationship between the structure and the behavior it produces. Based on the narratives, the model had eight main structures: gardeners, land, activities, quality of community garden, rules, trust, social relationships, and partners. The interaction between these sectors was based on several feedback loops which were grounded in the narrative. The model was able to produce both sustained and eroding community engagement. Among others, developing partnerships and how the various attribute of the garden such as quality, the amount of work, and social relationships played an important role in sustaining engagement

Net-zero building design: Demonstrating the use of agricultural waste and industrial by-products from rice cultivation belts

Buildings contribute significantly to global carbon emissions, resulting in high greenhouse gas emissions that contribute to global warming. Stubble burning is a major issue in India, causing severe health and environmental problems every year. The primary reason is the disposal issues associated with rice cultivation by-products such as rice straws and rice husk. This paper aims to explore the means of using building materials made of rice cultivation waste and by-products in making a Net-Zero energy office building, also the possibility of using waste heat from the biomass boilers in running the air conditioning system. A case study of a rice processing plant situated in Karnal, Haryana, where a 3600 m2 office building is planned was selected and iterative simulations were performed to analyse the step by step reduction in the annual EPI (Energy Performance Index) while incorporating energy saving strategies. Energy simulation software Design Builder v7.0 was used to assess the building performance. Life Cycle Assessment (LCA) was also performed to assess the reduction in initial carbon emissions while using low carbon building materials over conventional materials

Long term management challenges in diabetic patients with rhino-orbito-cerebral mucormycosis

There has been a recent upsurge in prevalence of diabetes mellitus in developing world. This has resulted in exponential increase in the incidence of both communicable and non-communicable diseases. Some of the infections increase morbidity and mortality associated with diabetes. Rhino-orbital-cerebral mucormycosis (ROCM) is one of the fatal opportunistic infections in diabetes. There is little data published regarding the short and long term management of patients suffering from this invasive fungal infection. Hereby, we report few cases of ROCM with varied presentations and their short and long term follow up. These patients were initially treated with injectable amphotericin B and later followed up with oral posaconazole

Advanced Dialer Based On Target Contact\u27s Activity

An advanced dialer system prioritizes modes of communication based on a target contact’s activity. The system, upon authorization by the user or target contact to access the user’s contacts, receives a selection of a target contact and checks the target contact’s activity status on all possible communication platforms. These communication platforms may include messaging applications using internet connectivity, traditional voice calling applications, video chat applications, etc. The system may further check the target contact’s network connectivity and feasibility of connection. The advanced dialer system calculates feasibility score for different communication platforms to reach the target contact. The system also ranks these communication platforms based on the calculated feasibility scores. The user may select the communication platform with the highest score/highest rank and communicate with the target contact. If the target contact is not reachable, the user may select the next highest ranked communication platform. The system automatically displays more likely dialing modes to the user, enabling easier communication

Complete plant regeneration of Valeriana wallichii DC. on auxin enriched medium and phytochemical analysis

Valeriana wallichii DC. (Valerianaceae) is a well-known medicinal herb distributed in Northwest Himalayas. The herb is utilized in the treatment of numerous ailments and diseases such as diarrhoea, diabeties, gastrospans, ulcer and wound healing, etc. Overexploitation, especially collection of rhizomes on a large scale for the medicinal purpose has significantly declined the availability of the herb in natural stands. Hence, there is a requirement of development of cultivation practices and protocol for mass propagation to achieve sustained utilization along with conservation of the species. In the present study, in-vitro culture of nodal segments on MS+2iP+IAA+2,4-D and MS+2iP+IAA+NAA resulted in multiple shoot induction along with regeneration of in-vitro roots on the same medium making the protocol cost-effective, efficient and comparatively less time-consuming. Moreover, the regeneration of adventitious roots from regenerated shoots enhanced the total number of plants obtained per explant as shoots with adventitious roots were individually excised and were transferred to natural conditions through the process of acclimatization. GC-MS analysis of a methanolic extract of leaves of the mother plant and micropropagated plant revealed the presence of 37 and 36 phytocompounds respectively. Phytocompounds including eucalyptol, neophytidiene, hexadecenoic acid, dimethyl palmitamine were identified to be present in the leaves of both mother and micropropagated plants whereas other compounds such as eicosyne, lilial, behenic alcohol were confined to be present in extract prepared from leaves of mother plant. Similary some phytocompounds (phytol, vinicizer, retinol) were detected in methanolic extract prepared from leaves of micropropagated plants

Extraction and characterization of oil from seeds of the medicinal plant Withania coagulans (Stocks) Dunal (Doda paneer)

Withania coagulans (Stocks) Dunal commonly known as Doda panner/ Indian Rennet is a well-known medicinal plant but remains underutilized mainly due to scarce distribution in nature and extremely poor germination rate. In the present study oil was extracted from seeds of Withania coagulans which was subsequently subjected to FTIR and GC-MS analysis to identify phytochemical components of extracted oil. FTIR analysis revealed presence of diverse group of compounds including alcohols, alkane, alkene, aldehyde, ketone and halo compounds. GC-MS analysis depicted presence of 49 phytoconstituents in the oil extracted from seeds of W. coagulans. among which hexanoic acid, n-hexadecenoic acid, Vitamin E, gamma-Tocopherol, squalene, fucosterol, 2-Pyrrolidinone, 1-methyl, octadecanoic acid represent major phytoconstituents identified. Several compounds identified to be present in extracted oil have been reported to possess one or more pharmacological activity. Hence, the study suggests validation of plant oil to be utilized as ingredient of different pharmacological, cosmetic and other food products

Effects of Aggressive Energy Efficiency Regulations on an Unprepared Building Sector using Uncertainty Analysis

Building Assessment Tools (BATs) are widely used to estimate the performance of building and to assist designers in making decisions. As building codes and rating systems move from prescriptive to performance-based metrics, BATs are increasingly used to show compliance. BATs use computational methods and the results are mostly in a single annualised metric. However, the scientific community has shown that aleatory factors such as occupant behaviour and weather make the potential energy use of a building far from being a single deterministic value. Also, it is known that there is a significant deviation between predicted (at design stage) and actual energy use in buildings. These variations reduce the credibility of the predictions, questioning the acceptance of BATs results without considering underlying errors. This problem is amplified in developing nations because of under-policed construction sector. To address this, our work analyses uncertainty in a typical air-conditioned multi-storey residential building’s performance in Delhi and shows implications of variable inputs in the results.The paper first reviews the use of BATs and existing studies on simulation uncertainty. Then uncertainty is evaluated in energy simulation of a sample building, including effects of inconsistent and construction practices. EnergyPlus is then fed values sampled (by Monte-Carlo method) from probability distribution functions of inputs (building fabric and operational parameters). Further sensitivity and uncertainty analysis of the results is performed. From the 3500 simulations, the most sensitive inputs found were internal gains; cooling setpoints and infiltration. The variation in cooling demand and discomfort hours is more than double between the best and worst case