Total Energy Savings Research Articles

Fostering Renewables into the Cold Chain: How Photovoltaics Affect Design and Performance of Refrigerated Automated Warehouses

In the industrial food supply chain, cold storage is one of the most important processes where there is a huge but still unused potential for employing renewable energy technologies. This paper analyses how the integration of rooftop photovoltaics affects the design and performance of refrigerated automated warehouses, which are becoming the preferred choice for frozen food storage facilities. The problem is modelled and solved by means of Constraint Programming. Results for the reference case in north-eastern Italy show that photovoltaic installation can lead to both yearly total cost and energy savings. Simulations highlight how design and performance of the refrigerated automated warehouse strictly depend on supply chain decision variables. PV integration offers supply chain managers more opportunities to act on the storage temperature and the incoming product temperatures strictly related to upstream and downstream stages of the whole cold chain. Attention should be paid to system throughput, which presents an intermediate range for which the design optimization of volume and surfaces reduces the convenience of PV integration. Simulations on facility locations reveal how different climate conditions affect the economic and environmental performance of the refrigerated warehouse, as well as country specific carbon intensity and energy price.

Consumer Acceptance Analysis of the Home Energy Management System

The purpose of this paper is to study consumer acceptance of the Home Energy Management System, which is the next generation electronic management system that the Korean government plans to implement in households. The Home Energy Management System is a critical device in maximizing the efficiency of electric energy consumption for each household by using a smart grid. Because it can visualize real-time price information on the electricity, households can easily monitor and control the amount of electricity consumption. With this feature, the Home Energy Management System can contribute to consumers’ total energy savings. This is a major reason why the Korean government wishes to implement it nationwide. Since the Home Energy Management System is a product that applies new technology that has not yet been directly encountered by consumers, there may be a difference in the level of public perception of the Home Energy Management System. Therefore, the impact of consumers’ awareness of the Home Energy Management System on their intention to use is important. To do this, the Technology Acceptance Model is utilized in this study. Traditional research on the Technology Acceptance Model includes awareness of usefulness and ease of use as well as intention to use. In contrast, in this research, an extended Technology Acceptance Model with four additional factors—economic benefit, social contribution, environmental responsibility, and innovativeness—that may affect the consumer’s awareness of usefulness and ease of use, is proposed. To collect the data, the survey was conducted with 287 respondents. As a result, the proposed model proved to be suitable in explaining the intention to use with a 70.3% explanation power. It is found that economic benefit (0.231) and innovativeness (0.259) impact on usefulness of the Home Energy Management System. Moreover, usefulness (0.551) has a bigger effect on intention to use than ease of use (0.338) does. Based on this, it is desirable for the Korean government to pursue a public relations strategy that emphasizes the economic benefits, social contributions, and environmental responsibility that will be gained when introducing the Home Energy Management System. It is effective to focus on consumers who are inclined to accept innovation. In addition, more effective results can be obtained by referring to the usefulness of the Home Energy Management System rather than referring to ease of use.

Shape control and whole-life energy assessment of an ‘infinitely stiff’ prototype adaptive structure

A previously developed design methodology produces optimum adaptive structures that minimise the whole-life energy which is made of an embodied part in the material and an operational part for structural adaptation. Planar and complex spatial reticular structures designed with this method and simulations showed that the adaptive solution achieves savings as high as 70% in the whole-life energy compared to optimised passive solutions. This paper describes a large-scale prototype adaptive structure built to validate the numerical findings and investigate the practicality of the design method. Experimental results show that (1) shape control can be used to achieve ‘infinite stiffness’ (i.e. to reduce displacements completely) in real-time without predetermined knowledge regarding position, direction and magnitude (within limits) of the external load; (2) the whole-life energy of the structure is in good agreement with that predicted by numerical simulations. This result confirms the proposed design method is reliable and that adaptive structures can achieve substantive total energy savings compared to passive structures.

Unravelling the potential of energy efficiency in the Colombian oil industry

The oil and gas sector represents 39% of the world's total industrial final energy consumption, and contributes to around 37% of total greenhouse gas (GHG) emissions. This study investigates the potential for improvements in energy efficiency, and their implications for CO2 abatement, in the Colombian oil industry value chain. It also assesses the potential cost of conserved energy and mitigated CO2-eq. A bottom-up approach was used to identify energy efficiency measures based on an assessment of specific operational data at the process unit level. In total, 20 measures and technologies were identified and applied in 48 cases throughout the chain, representing energy savings of 15.8 PJ and GHG savings of 0.75 Mt CO2-eq per year. This accounts for 25% and 19% of the total energy consumption and GHG emissions, respectively. Ninety-six percent of the total energy savings come from measures that are already cost-effective and could be implemented in the short term. The results of this study offer a better understanding of the critical stages for energy and GHG savings potentials, as well as investment cost and revenue from a full value chain perspective, based on operational data processing.

Evaluation of Heat Transfer Performance between Rock and Air in Seasonal Thermal Energy Storage Unit

Ventilation is one of the most energy demanding parts of deep underground mining operations due to the extensive amounts of energy needed to cool (or heat) the substantial amount of air flow in underground workings. This considerable amount of energy demand can be partially satisfied by extracting renewable energies or using alternative energy solutions available at mine sites. In Canada, some mining operations have the opportunity to create a Seasonal Thermal Energy Storage (STES) unit by blowing mine intake air through large volumes of rock mass dumped in a decommissioned pit. This technique allows for creation of the so-called “Natural Heat Exchanger (NHE)” which moderates seasonal air temperature oscillations. This paper signifies a novel heat transfer model for performance assessment of a NHE system. It investigates the potential for energy savings by implementation of variable number and position of ventilation trenches in underground mines. In this regard, a 3-D heat transfer model is developed to evaluate the thermal storage and the heat transfer between broken rock mass and ventilated air flow and also to specify how design parameters such as position and number of ventilation trenches will affect the heat transfer performance as well as the total energy savings. The results of this study show that NHE can be applied in thermal management of underground mines with the aim of decreasing energy consumption for heating, cooling and ventilation purposes.

Vehicle energy consumption and an environmental impact calculation model for the transportation infrastructure systems

The interaction of vehicles and tires with various surface and structural features of roadways impact rolling resistance, hence fuel consumption of vehicles. Efficient interaction of vehicles with the roadway provides new opportunities to reduce transportation systems environmental impacts. A roughness–speed impact (RSI) model was developed to quantify the energy and environmental impacts due to vehicle–pavement interaction. The RSI model accounts for the additional rolling resistance of vehicles resulting from pavement surface properties measured in terms of smoothness as well as vehicle efficiency improvements over time. The model uses vehicle-specific power as a basis to develop the analytical equations for representing vehicle–pavement interaction. The proposed analytical model offers advantages for easy integration to LCA software to evaluate GHG reduction policies. According to the model, one unit change of IRI (63.36 in/mile) results in an average increase in fuel consumption of 3% and 2%, respectively, at high and low speeds (65 and 35 mph) for passenger cars. Heavier trucks are less sensitive to IRI change; and one unit change in IRI on average results in 2% and 1% increase, respectively, in fuel consumption of heavy truck at high and low speeds. This paper presents case studies to explore effectiveness of a short-term policy goal concerning with the management of roadway surface features. According to the LCA results with different scenarios of pavement management policies, while vehicle efficiency accounts for about 27% of the potential total energy savings, potential savings from pavement roughness can be up to 7%.

Effects of energy efficiency measures in district-heated buildings on energy supply

Abstract In this study we estimate the final and primary energy savings for different energy efficiency measures in a multi-apartment building when heated by small-, medium- or large-scale district-heat production systems (DHSs). The small-scale system is based on heat-only boilers, whereas the other two also include cogeneration of district heat and electricity. In the systems with cogeneration units, a change in building's heat demand may influence cogenerated electricity and hence the overall power system. For the building analyzed, the estimated annual total final heat and electricity savings were 136 (54%) and 30 MWh (52%), respectively, giving total annual primary energy savings of 177–289 MWh. This varies as the ratio of primary and final heat savings depends on the type of energy efficiency measure and the energy supply. For the same heat savings measure, a system with a heat-only boiler gave the highest primary energy savings, whereas a system based mostly on cogeneration of district heat and electricity in combination with averaged-efficiency standalone power plants gave the lowest primary energy savings. When the energy supply is based on energy-efficient renewable-based system, the differences in primary energy savings between large- and small-scale DHSs are minor for the same energy efficiency measure.

INFLUENCES OF SHORT-TERM VARIATIONS ON ENERGY-SAVING OPPORTUNITIES IN A PULP MILL

Significant opportunities for energy savings are identified in the hot and warm water system of a kraft pulp mill. Short-term variations in the process are studied in order to identify and quantify the influences of these variations on the energy-saving opportunities. Daily and ten-minute averages of measured data are used as varying input data in a heat exchanger network with fixed heat transfer areas. When the short-term variations are considered, the total energy savings are decreased by about 10%. The steam-saving opportunities correspond to at least 5% of the mill’s total steam use, when the short-term variations are considered. At least 65% of the influences of short-term variations are detected already when the seasonal variations are considered.

Techno-economic potential of large-scale energy retrofit in the Swiss residential building stock

A statistical analysis of more than 6,000 energy performance certificates including retrofit options proposed by experts for different building elements is performed. This provides an overview of the most commonly suggested renovation measures and their estimated investment costs and U-Values. Based on an energy model of the Swiss residential building stock (SwissRes), the theoretical energy savings are estimated. Together with the estimated investment costs, the levelized costs of each renovation measure is then determined in order to identify the most cost-effective measures. It is shown that a large-scale energy retrofit of the residential building stock would result in theoretical energy savings of up to 84% regarding the current simulated energy demand. Yet, existing technical and social constraints would lower the expected energy savings significantly. None of the selected measures is cost-effective, but under a more optimistic scenario, the cost-effective share reaches up to 85% of the total potential energy savings.

The Potential of Smart Technologies and Micro-Generation in UK SMEs

Small-to-medium-sized enterprises (SMEs) make up 99% of businesses and contribute 13% of energy demand globally. However, much of the demand-side energy research and policy attention to date has focused on the domestic, large commercial and industrial sectors. Previous research on SMEs has primarily concentrated on the drivers and barriers to the adoption of energy efficiency measures. However, less attention has been given to other areas of demand-side management in SMEs, such as the role of ‘smart’ technologies and micro-generation. The paper aims to contribute to filling this gap. To analyse the potential of smart technologies in UK SMEs, a quantitative model is developed to assess seven categories of smart technologies in ten non-domestic sectors. Overall, the results suggest that smart technologies within the UK SME market offer significant estimated annual energy savings potential of ~£8.6 billion against an estimated energy spend of ~£49.7 billion (representing ~17% savings potential on energy expenditures). From the smart technology categories examined, fleet management, integrated building management systems and smart meters have the potential to offer the greatest energy savings to SMEs, providing estimated total energy savings of ~£7.5 billion annually. To analyse the potential of micro-generation in UK SMEs, interview-based qualitative research was undertaken with 17 SMEs to explore the drivers and barriers to its adoption. The research found that the initial costs, technical feasibility and planning permission on historical buildings were the main barriers, and that the ‘green’ marketing potential of micro-generation, coupled with ethical reasons and feed-in tariffs, were the main drivers.

Office buildings with electrochromic windows: A sensitivity analysis of design parameters on energy performance, and thermal and visual comfort

In this paper, a representative office building zone with an electrochromic (EC) glazed façade was simulated in TRNSYS and Radiance/Daysim for a large number of different combinations of design parameters (i.e. location, façade orientation, window control, window-to-wall ratio, internal gains, thermal mass and envelope air tightness). Results of energy consumption, peak energy demand, useful daylight index (UDI) and predicted percentage of persons dissatisfied (PPD) for a total of 7680 scenarios were obtained and used in a sensitivity analysis considering the Main effect of the building parameters. The relative influence of the parameters is presented and the different designs improving the outputs are determined. Results have shown that the greatest total energy savings considering EC windows are for warmer climates with higher solar radiation exposures. The presence of an EC window mostly influences the cooling peak load and acts as an alternative solution to thermal mass from the perspective of peak reductions. While the choice of the specific window control strategy is having a limited impact on the energy savings and peak load reductions, the analysis revealed that this parameter has a larger impact on the visual comfort (UDI). The use of smart window does not appear to greatly influence the thermal comfort within the zone (small impact on the PPD).

Determining a Practically Optimal Overhang Depth for South-Facing Windows in Hot Summer and Cold Winter Zone

This study investigated the building energy, glare and daylight performance of overhang using building simulation software Energyplus in order to identify an optimal depth in hot summer and cold winter zone. A typical building with different window-to-wall ratios (WWR) was modeled and different overhang depths were considered. Results showed that the optimal overhang depths are 0.9m (WWR=0.15), 1.16m (WWR=0.3) and 1.62m (WWR=0.57), respectively. The total energy savings from overhang design can be ranging from about 3% to 24% depending on WWR and overhang depth. Moreover, the regression relationship between optimal overhang depth and WWR is given to help identify the best overhang dimension at the design stage. The potential energy saving performance for different WWRs then can be roughly inferred according to a total energy saving chart without building energy simulation. In conclusion, to be applicable in buildings, an overhang depth of 0.6-0.8m is suitable in this region since it has a balance in energy performance and aesthetic appearance.

Energy utilizability concept as a retrofitting solution selection criterion for buildings

Retrofitting is widely explored as one of the energy conserving opportunities for existing buildings, in which both passive and active solutions are carefully evaluated. However, when different retrofitting solutions are combined and applied to a building, the total energy savings potential, which is less than the sum of the savings from applying the various individual retrofitting solutions, is considerably reduced and the synergies among the various technologies need to be understood and evaluated. In this study, the concept of utilizability is employed for the analysis of multiple energy retrofitting solutions in buildings and is defined as the ratio of energy savings derived from applying combined solutions to a building over the sum of individual energy savings from applying individual solutions. It is aimed at providing a better understanding of the combined retrofitting solutions. The sensitivity analysis on the utilizability value further pro­vides a selection criterion for retrofitting solution selection.

Optimal design of modular cogeneration plants for hospital facilities and robustness evaluation of the results

The widespread adoption of combined heat and power generation is widely recognized as a strategic goal to achieve significant primary energy savings and lower carbon dioxide emissions. In this context, the purpose of this research is to evaluate the potential of cogeneration based on reciprocating gas engines for some Italian hospital buildings. Comparative analyses have been conducted based on the load profiles of two specific hospital facilities and through the study of the cogeneration system-user interaction. To this end, a specific methodology has been set up by coupling a specifically developed calculation algorithm to a genetic optimization algorithm, and a multi-objective approach has been adopted. The results from the optimization problem highlight a clear trade-off between total primary energy savings (TPES) and simple payback period (SPB). Optimized plant configurations and management strategies show TPES exceeding 18% for the reference hospital facilities and multi–gas engine solutions along with a minimum SPB of approximately three years, thereby justifying the European regulation promoting cogeneration. However, designing a CHP plant for a specific energetic, legislative or market scenario does not guarantee good performance when these scenarios change. For this reason, the proposed methodology has been enhanced in order to focus on some innovative aspects. In particular, this study proposes an uncommon and effective approach to identify the most stable plant solutions through a multi-objective robust design optimization. In particular, the sensitivity of the expected results to possible difficulties in finding commercially available CHP gas engines with sizes reasonably close to the optimal numerical solutions has been estimated. The results indicate that the economic sensitivity is often higher than the energetic sensitivity for most of the optimal solutions, with standard deviation accounting up to 7% of its mean value for the SPB, whereas that percentage is always under 3% for the TPES. Furthermore, the research highlights how the expected results obtained through a deterministic definition of the input decision variables could be overestimated compared to the robust design approach. The proposed research also highlights how optimized CHP plants can be characterized by reasonable levels of energetic and economic sensitivity to changes in the following variable quantities: selling price of electricity, reference efficiency of the Italian thermoelectric generation and selling price of the energy efficiency certificates recognized by the Italian legislation. Indeed, Pareto optimal solutions indicate that the standard deviation for the SPB is always less than 3.5% of its mean value, while this percentage is always under 7% for the TPES.

Potential energy savings from deployment of Dynamic Insulation Materials for US residential buildings

This paper presents a summary of the results obtained from a comprehensive analysis to evaluate the potential energy savings associated with replacing traditional, static insulation with Dynamic Insulation Materials (DIMs) for US residential buildings. In order to determine the effectiveness of DIMs to reduce heating and cooling energy use, two different control schemes are investigated: 1) using temperature sensors and the measured temperature profile to trigger the switching mechanism, 2) seasonal control based on climate and weather trends. The performance of DIMs varied significantly by climate, with total energy savings ranging from 7% to 42%.

Assessing the impacts of transport policies through energy system simulation: The case of the Medellin Metropolitan Area, Colombia

The transport sector contributes to climate change, and it has been the target of public interventions to improve quality of life and reduce CO2 emissions. The Medellin metropolitan area (Colombia) has developed a mass transportation system called Metro de Medellin that integrates train lines, a tram line, BRTs, gondola lift systems, a bicycle-sharing system and hybrid buses to reduce traffic and CO2 emissions. Despite these efforts, pollution is peaking, and the situation requires new plans. The aim of this paper is to quantify the emissions that will be avoided by the implementation of Medellin's Master Plan, the promotion of telecommuting, and the development of a transport energy model for Medellin between 2010 and 2040. The results indicate that combining the promotion of mass transportation and telecommuting could represent 5.65 MTons of CO2 equivalent avoided by 2040 (9.4% reduction) and estimated total energy savings of 86,575.55TJ. Therefore, it is necessary to implement complementary policies in order to achieve the commitment assumed by Colombia at the COP 21. The analytical framework used here could be applied to other regions in order to evaluate environmental and energy mitigation strategies, especially in the developing world where similar policies may be in place.

Potential life cycle energy savings through a transition from typical to energy plus households: A case study from Thailand

Through a comparative life cycle analysis of typical, nearly net zero, net zero and energy plus houses in Thailand, each having a net floor area of 141.4m2; this study demonstrates that the operational electricity demand of typical houses can be reduced by 37% by incorporating various energy saving measures and goes further to establish that this reduced demand can be partially, fully or-over met through in-house electricity generation by solar photovoltaic. Over a period of 50 years, the transition from typical to nearly net zero and net zero energy houses is assessed to offer total life cycle primary energy savings of about 69% and 86%, respectively; while the energy plus house is assessed to have (i) a potential of feeding in 7450kWh of electricity into the public grid each year and (ii) the capability of being energy neutral in a life cycle perspective over a duration of 16 years. The embodied energies through the evolution from typical to energy plus houses are however noted to grow up to 214%, mainly because of the manufacture of photovoltaic panels.

(Keynote) Recent Trend in New and Renewable Energy Generation in Korea and KIER’s R&D Activities

In order to address climate change and to create new energy industries, Korea has been actively developing and deploying new and renewable energy (NRE) technologies. According to the second national basic plan for energy, 11% of total energy and 13.4% of total electric energy will be provided by NRE. 20% of NRE will be generated from wind power and 14% will be supplied by solar power plants. To promote the distribution of NRE, the Korean Government introduced subsidy programs and regulatory methods which include a FIT (feed-in-tariff) by 2011 and a RPS (renewable portfolio standard) from 2012, which forces major power companies to increase supply from NRE sources from 2% (at the beginning of 2012) to 10% of total power generation by 2022. After adopting the RPS, the deployment of NRE has increased dramatically. In April 2016, the total generation capacity of NRE was 9.2% of the total domestic electric generation, 102.5 GW. About half of this generation is from renewable energy resources. By the end of 2015, the installed capacities of PV, wind power and fuel cells were 2,537MW, 804.85MW, and 252MW, respectively. These figures are significantly larger from what they were under the FIT scheme in 2011: 554 MW, 405.345MW, and 50MW, respectively. During the same period, 2,200 units of residential fuel cell systems were installed under the green home program. National policies have played an important role in RD&D of NRE. After enacting the ”Promotion Act for the Development of Alternative Energy” in 1987, the Korean Government has been pushing RD&D of NRE. PV, wind power and fuel cells were identified as 3 of the highest priority core technologies. The Korean Government newly announced the action plans to meet the policy objectives for addressing climate change, comprising 6 core technologies to be developed as national growth engines: PVs, fuel cells, ESS, biofuels, power IT, and CCS technologies. Those technologies will contribute to create new energy markets, such as eco-friendly towns, self-sufficient islands, and zero energy buildings. To meet the objectives of national energy plans by improving and expanding advanced energy technologies, KIER has established 6 major R&D areas: including distributed generation through new and renewable energy, energy networks, and next generation batteries. As clean distributed generation technologies, KIER has been developing 50 to 100 μm ultra-thin silicon solar cells (KUT cell), 25% efficient CIGS thin-film solar cells, and hydrogen fuel cell technologies. KIER developed fuel cell-battery hybrid vehicles and residential fuel cell systems. KIER is trying to develop the core technologies for off-shore wind farms at Jeju’s global research center, where convergence R&D is being conducted for carbon-free islands on areas such as marine bio-energy, salinity gradient power, and floating off-shore wind power. To promote NRE distribution, KIER has been developing micro energy grid technologies and various energy storage systems, such as large capacity redox flow batteries, supercapacitors, and Li-S batteries. For about 20 years, KIER has been developing and demonstrating near zero energy building technologies using passive and active solar design. In 2009, through the test of the second model of low energy houses, 85% of total energy savings, including electric and thermal energy, was achieved. In 2013, KIER successfully applied the technology to 29 actual homes. From 2014, KIER has been designing an eco-friendly energy town at the Innovation City in Chungbuk Province as one of 3 Korean Government-sponsored demonstration projects. The government wanted to solve not only energy and environment problems, but also NIMBY problems to change NIMBY facilities to eco-friendly generation facilities using renewable energy technologies. One of the projects is to build an eco-friendly campus at a sewage treatment facility near a small town using renewable energy hybrid systems, such as solar thermal systems with seasonal energy storage systems, PVs, and fuel cells. The advanced energy technologies developed by KIER will contribute to Korea’s national policy of expanding renewable energy technologies to 11% of primary energy consumption and reduce greenhouse gas emissions to 37%.

Analysis of energy savings of three daylight control systems in a school building by means of monitoring

Daylight control systems, which automatically adjust the artificial light levels depending on the daylight penetration, can result in substantial energy savings. However, their energy saving potential cannot be estimated accurately because it depends on several building and system parameters, climate conditions, occupant behaviour and type and commissioning of the daylight control system. The objective of this paper is to compare the energy saving potential and operation of different daylight control systems in school buildings. One year monitoring has been carried out simultaneously in 3 neighbouring classrooms, equipped with a different type of control system. The active power and the electric energy consumption of the artificial lighting were measured continuously on a minute-by-minute basis, as well as the occupancy of the classrooms and the global irradiance outside the building under an unobstructed horizon. Momentary visual comfort assessments were carried out in the classrooms.Although all classrooms have comparable occupancy and identical building characteristics, differences between the annual energy savings of the different daylight control systems are found to be significant: the total annual energy savings varied from 18% to 46%. Under the given conditions, the open loop system with the outward facing daylight sensor was noticed to yield the largest while the closed loop system with centrally positioned sensor produced the smallest savings. However, it has to be made sure that the energy savings are not at the expense of the visual comfort. The performance of the systems regarding both energy savings and visual comfort is related to the operation and the initial commissioning. An in-depth analysis of the monitoring campaign is discussed to explain the differences in energy savings and visual comfort. The energy savings due to the implementation of a daylight control system are divided into on the one hand dimming due to daylight penetration and on the other hand initial dimming to compensate for the over dimensioning of the lighting system and to take into account constant illuminance control.

Explaining the historical energy use in dwelling stocks with a segmented dynamic model: Case study of Norway 1960–2015

A segmented dynamic dwelling stock model is proven useful for understanding the development and changes of ageing building stocks, which is highly relevant for renovation measures and estimates of energy use and emissions in aggregated building stocks. In this paper, such a model is developed further for detailed analyses of dwelling stock energy demand and exemplified for the Norwegian dwelling stock 1960–2015. The dwelling stock model simulates the development in stock size and composition and is combined with archetype-specific energy intensities to estimate the total energy demand. After calibrating the model results with statistics, the model is used to explore the phenomena and causes of historical changes. A large-scale improvement of the energy efficiency of the Norwegian dwelling stock has taken place through renovation and construction of new dwellings. A historical shift to more efficient energy carriers and heating systems has had an effect on energy savings in the system, of the same size as the effect of the improved energy efficiency of the stock. However, the total average energy savings per m2 are offset by changes in user heating habits. A significant decrease in average delivered energy intensity per m2 is only observed after the introduction of heat pumps.