Direct Energy Savings Research Articles

Carbon emission calculation and uncertainty analysis of asphalt concrete during the production stage

Asphalt concrete is the main material consumed by road engineering. At present, there is no uniform standard for determining the carbon emissions of different types of asphalt concrete, and the calculation process is uncertain. In this study, a carbon emission calculation method that combines theory with practice is proposed. First, a theoretical carbon emission model based on the heat balance equation and an actual carbon emission model based on actual energy data are established, and the key links in the carbon emissions of asphalt concrete are determined. Second, the carbon emission correction factors of five different types of asphalt concrete are obtained to estimate the actual carbon emissions more accurately. Finally, the uncertainty of the parameters is evaluated and characterized via the DQI-Monte Carlo simulation method. The results show that the carbon emissions from large to small are modified asphalt concrete (MAC) > ordinary asphalt concrete (AC) > stone matrix asphalt (SMA) > recycled asphalt concrete (ZAC) > warm mix asphalt concrete (WAC). The aggregate heating stage is the key link in the carbon emission of asphalt concrete. Controlling the aggregate heating temperature and moisture content is the most direct and efficient energy savings and emission reduction measure.

Pathway to Decarbonization Through Industrial Energy Efficiency: Micro and Macro Perspectives from Compressed Air Usage

Energy audits directly provided the industrial sector with reduced energy costs and avoided emissions. Still, they also lead to far-reaching indirect and induced local, regional, and national benefits. This paper aims to present the techno-economic-environmental analysis to achieve decarbonization through implementing industrial energy efficiency at micro and macro levels. An integrated techno-economic-environmental methodology is developed. Case studies of micro-level carbon reduction efforts through industrial energy efficiency technologies are presented. The broader macroeconomic and environmental effects of technology on society are analyzed using data from 206 energy audits of industrial compressed air systems conducted over 13 years. The impacts show that energy-efficient improvements lead to direct cost savings for manufacturers, boost economic activity across sectors, and affect carbon dioxide emissions both short-term and long-term in the region. Given their extensive benefits, energy audits significantly influence policymaking. We devised a methodology to link micro-level energy audit data with macroeconomic and environmental analyses to quantify these cascading benefits. The economic scenario analysis shows that $228 M has been saved from direct industrial energy savings from implementing all compressed air recommendations in the studied periods and the region. In addition, the investment made through manufacturers would create 2,025 jobs and $383 M annually, cascading regional economic impacts. The environmental analysis shows that the regional manufacturers have directly avoided about 2.8 M metric tons of carbon dioxide emissions.

Direct or indirect energy savings in food and beverage services? Visitors′ preferences in hotel restaurants

Food processing in hotels is one of most energy-intensive activities in the tourism industry. There is an urgent need to reduce energy consumption in hotels to limit their environmental impact. This research aims to assess tourists' preferences for the provision of food that require low energy preparation and to compare them with tourists’ preferences for other indirect energy saving options. A quantitative survey with 944 tourists visiting six tourist sites across the Czech Republic was used for primary data collection. Data were analyzed using linear regression models. Our findings signal that direct energy savings tend to be perceived differentially and surprisingly as the least preferred option among tourists. Those who support direct energy savings in food processing are rather older respondents and also respondents who declare stronger pro-environmental everyday behaviour and subjective norms. We claim that as tourists show highly diverse preferences for various ways of energy savings, we need to ensure that multiple energy saving options are offered so that tourists contribute to reducing the ecological footprint of hotels. At the same time, it has to be highlighted that only few surveyed tourists voluntarily accepted reduction of comfort in the food and beverage provision. There is room for many technological and social innovations and raising environmental awareness among tourists to overcome this contradiction.

Labour productivity improvements from energy efficiency investments: The experience of European firms

Energy efficiency investments are essential to transition to a carbon-neutral economy. Nevertheless, despite being financially viable, many energy efficiency investment opportunities do not materialise. The existing literature attributes this situation to financial and non-financial factors. Research suggests that many firms focus only on direct energy savings and neglect non-energy benefits that include increased labour productivity. Up to date, due to the lack of high-quality data, few studies attempted to quantify how the energy efficiency investments affect firm-level outcomes other than the reductions in energy consumption. This paper overcomes this barrier by using novel data from a firm-level survey conducted by the European Investment Bank. The survey covers more than 15,000 firms in 27 European Union member states and the United Kingdom during 2018–2019. This study investigates the relationship between the energy efficiency investments and the labour productivity of the European firms and uses instrumental variables methodology to account for potential endogeneity. The results show a positive and causal relationship between energy efficiency investments and labour productivity. The findings of the paper suggest that firms can benefit much more from the energy efficiency investment than what is often assumed, and highlight a need for government policies that would increase firms’ awareness of the non-energy benefits.

Identification of everyday food-related activities with potential for direct and indirect energy savings: KTH Live–in–Lab explorative case study

This exploratory study analyses the daily activities of the end-user in terms of assessing the potential for conserving direct and indirect energy. In the course of the study, a socio-technological system approach was applied, which made it possible to combine the methods of analysis and interaction of the social group (students) and technical infrastructure (living laboratory). The method of creating personas was also applied to segregate a large group of the population within one segment. This approach allowed us to consider in more detail the different types of behavior in the same segment. As a result, we got more personalized strategies for changing a behavior tailored for each individual persona. In conclusion, a recommendation was given on which policies implications and to which organizations to address.

Toward a method for assessing the energy impacts of telecommuting based on time-use data

Most telecommuting (TC) studies focus on travel impacts and do not consider changes in time spent on non-travel activities (e.g. ‘leisure’) and the energy impacts of these changes. We demonstrate a time-use approach to assess interrelations between changes in commuting time and time spent on travel and non-travel activities and associated energy impacts. Time-use data analysis shows that spending less time on commuting is associated with more time spent on ‘sleep’, ‘leisure’, ‘personal, household and family care’, ‘private travel’ and ‘eating and drinking’. Substituting car commuting with ‘sleep’, ‘eating and drinking’, common ‘leisure’ and ‘personal, household and family care’ activities is likely to reduce energy requirements as these are associated with less energy requirements than car commuting. This is different for ‘private travel’, ‘meal preparation at home’, and energy-intensive or out-of-home ‘leisure’ activities, which are associated with relatively high energy requirements. The commute modal split is a key variable in energy impacts of TC, because transport modes differ in their energy requirements. While car commuters can realize high energy savings through TC, for people who usually bike or walk to work, direct energy savings through reduced commuting are zero. Thus, any additional energy impact due to substitute activities, increases net direct energy requirements. Future research should further investigate the relationship between TC and time spent on (non-)travel activities and the marginal energy requirements of these activities. If so, the time-use approach can become key for assessing energy impacts of TC and other applications which impact individual time allocation.

Labour Productivity Improvements from Energy Efficiency Investments: The Experience of European Firms

Energy efficiency investments are essential for transitioning to a carbon-neutral economy. Nevertheless, many energy efficiency investment opportunities do not materialise. The existing literature attributes this situation to financial and non-financial factors. Research suggests that many firms focus only on direct energy savings and neglect non-energy benefits that include increased labour productivity. Up to date, due to lack of high-quality data, few studies attempted to quantify the effects of the energy efficiency investments on firm-level outcomes other than the reductions in energy consumption. This paper overcomes this barrier by using novel data from a firm-level survey conducted by the European Investment Bank that covers more than 15,000 firms in 27 European Union member states and the UK during 2018-2019. It studies the relationship between the energy efficiency investment and the labour productivity of the European firms, utilising instrumental variables methodology to account for potential endogeneity. The results show a positive and causal relationship between energy efficiency investment and labour productivity. The findings of the paper suggest that firms can benefit much more from the energy efficiency investment than what is often assumed, and highlight a need for government policies that would increase firms’ awareness of the non-energy benefits.

The Economics of Energy Efficiency in Developing Countries

Almost all of the world’s energy demand growth is projected to occur in low- and medium-income countries (LMICs). Targeted energy efficiency investments have the potential to mitigate tensions between economic growth objectives and sustainable development commitments. We review the empirical evidence on both the private and social benefits of energy efficiency improvements in LMICs. In addition to direct energy savings, energy efficiency investments can generate indirect benefits such as improved reliability, enhanced energy access, and increased productivity. We highlight the role that energy subsidies, unreliable power supply, and capital constraints may play in the underinvestment in energy efficiency. Increasingly, LMICs are implementing policies and programs aimed at mitigating these barriers. We discuss some recent policy design innovations and emphasize the importance of rigorous evaluation.

EIB Working Paper 2021/07 - Can European businesses achieve productivity gains from investments in energy efficiency?

Energy efficiency investments are essential for transitioning to a carbon-neutral economy. Nevertheless, despite being financially viable, many energy efficiency investment opportunities do not materialise. The existing literature attributes this situation to financial and non-financial factors. Research suggests that many firms focus only on direct energy savings and neglect non-energy benefits that include increased labour productivity. Up to date, due to lack of high-quality data, few studies attempted to quantify the effects of the energy efficiency investments on firm-level outcomes other than the reductions in energy consumption. This paper overcomes this barrier by using novel data from a firm-level survey conducted by the European Investment Bank that covers more than 15,000 firms in 27 European Union member states and the UK during 2018-2019. It studies the relationship between the energy efficiency investment and the labour productivity of the European firms, utilising instrumental variables methodology to account for potential endogeneity. The results show a positive and causal relationship between energy efficiency investment and labour productivity. The findings of the paper suggest that firms can benefit much more from the energy efficiency investment than what is often assumed, and highlight a need for government policies that would increase firms' awareness of the non-energy benefits.

Costs of energy efficiency mandates can reverse the sign of rebound

Improvements in energy efficiency reduce the cost of consuming services from household cars and appliances and can result in a positive rebound effect that offsets part of the direct energy savings. We use a general equilibrium model to derive analytical expressions that allow us to compare rebound effects from a costless technology shock (CTS) to those from a costly energy efficiency standard (EES). We decompose each total effect on the use of energy into a direct efficiency effect, direct rebound effect, and indirect rebound effect. We show which factors determine the sign and magnitude of each. Rebound from a CTS is generally positive, as in prior literature, but we also show how a pre-existing EES can negate the direct energy savings from the CTS – leaving only the positive rebound effect on energy use. Then we analyze increased stringency of an EES, and we show exactly when the increased costs reverse the sign of rebound. Using plausible parameter values in this model, we find that indirect effects can outweigh the direct effects captured in partial equilibrium models, and that the total rebound from a costly EES can be negative.

General equilibrium rebound from energy efficiency innovation

Energy efficiency improvements “rebound” when economic responses undercut their direct energy savings. I show that general equilibrium channels typically amplify rebound by making consumption goods cheaper but typically dampen rebound by increasing demand for non-energy inputs to production and by changing the size of the energy supply sector. Improvements in the efficiency of the energy supply sector generate especially large rebound because they make energy cheaper in all other sectors. Quantitatively, general equilibrium channels reduce rebound in U.S. consumption good sectors from 39% to 28% but increase rebound in the energy supply sector from 42% to 80%.

Costs of Energy Efficiency Mandates Can Reverse the Sign of Rebound

Improvements in energy efficiency reduce the cost of consuming services from household cars and appliances and can result in a positive rebound effect that offsets part of the direct energy savings. We use a general equilibrium model to derive analytical expressions that allow us to compare rebound effects from a costless technology shock to those from a costly energy efficiency mandate. We decompose each total effect on the use of energy into components that include a direct efficiency effect, direct rebound effect, and indirect rebound effect. We investigate which factors determine the sign and magnitude of each. We show that rebound from a costless technology shock is generally positive, as in prior literature, but we also show how a pre-existing energy efficiency standard can negate the direct energy savings from the costless technology shock – leaving only the positive rebound effect on energy use. Then we analyze increased stringency of energy efficiency standards, and we show exactly when the increased costs reverse the sign of rebound. Using plausible parameter values in this model, we find that indirect effects can easily outweigh the direct effects captured in partial equilibrium models, and that the total rebound from a costly efficiency mandate is negative.

Constructing policy success for UK energy feedback

ABSTRACTEnergy-feedback tools are commonly used to promote energy saving. In the UK, energy-feedback provision (currently via an in-home display) is part of the government-mandated roll-out of smart meters to all homes by 2020. A core assumption underlying this widespread provision is that information, or evidence, can lead to positive changes in action. This is analogous to assumptions underlying the notion of ‘evidence-based policy’, and raises questions about how users, researchers and policy-makers go about using evidence when aiming for a ‘successful’ outcome. In addition, the ‘policy feedback’ research agenda has asked how policies alter the landscapes within which they operate by, for example, affecting relationships between actors. Via an in-depth review of Department of Energy and Climate Change (DECC) policy literature over 2010–16, the UK smart meter roll-out was analysed in terms of how its energy-feedback-focused measures may be deemed as ‘successful’. Findings include the fact that direct energy savings played a smaller role than might be expected, and translation from one success measure to another was repeatedly observed. A key conclusion is that acting on feedback requires an assessment of success, but such assessment is highly contextual, for consumers and policy-makers alike. Ways to increase reflexivity in this area are discussed.

Environmental benefits from ridesharing: A case of Beijing

Emerging ridesharing travel could be an effective way in China to reduce travel demand by cars, which can further seek to shift personal transportation choices from an owned asset to a service used on demand and lessen the traffic jam and emissions. Drawing on the raw observed ridesharing trip data provided by DiDi Chuxing company, this study evaluated the direct environmental benefits of ridesharing resulted from the travel mode shift and the indirect environmental benefits resulted from the attitude change towards car purchase behavior. The megacity Beijing is taken as the empirical context given its more serious situation of traffic congestion and difficulties for car purchase. Estimation results show that direct annual energy savings made by ridesharing are approximately 26.6 thousand tce, and annual emission reductions of CO2 and NOx are approximately 46.2 thousand tons and 253.7tons, respectively. Besides, using ridesharing service will lead to substantial energy savings and emission reductions from the long-term perspective attributing to the weakening willingness on purchasing new cars. Promoting EVs among ridesharing vehicles and switching to clean electricity generation as well as improving vehicle efficiency can further enhance the environmental benefits of ridesharing, with maximum effects amounting to 67% of energy savings and 57% of CO2 emission reductions compared to 2016 level of the fuel-related energy consumption and emissions made by ridesharing.

Analysis of energy end-use efficiency policy in Spain

The implementation of saving measures and energy efficiency entails the need to evaluate achievements in terms of energy saving and spending. This paper aims at analysing the effectiveness and economic efficiency of energy saving measures implemented in the Energy Savings and Efficiency Action Plan (2008–2012) (EAP4+) in Spain for 2010. The lack of assessment related to energy savings achieved and public spending allocated by the EAP4+ justifies the need of this analysis. The results show that the transport and building sectors seem to be the most important, from the energy efficiency perspective. Although they did not reach the direct energy savings that were expected, there is scope for reduction with the appropriate energy measures. For the effectiveness indicator, the best performance are achieved by public service, agricultural and fisheries and building sectors, while in terms of energy efficiency per monetary unit, the best results are achieved by transport, industry and agriculture sectors. Authors conclude that it is necessary that central, regional and local administrations will get involved, in order to get better estimates of the energy savings achieved and thus to affect the design of future energy efficiency measures at the lowest possible cost to the citizens.

Modelling the impact of social network on energy savings

It is noted that human behaviour changes can have a significant impact on energy consumption, however, qualitative study on such an impact is still very limited, and it is necessary to develop the corresponding mathematical models to describe how much energy savings can be achieved through human engagement. In this paper a mathematical model of human behavioural dynamic interactions on a social network is derived to calculate energy savings. This model consists of a weighted directed network with time evolving information on each node. Energy savings from the whole network is expressed as mathematical expectation from probability theory. This expected energy savings model includes both direct and indirect energy savings of individuals in the network. The savings model is obtained by network weights and modified by the decay of information. Expected energy savings are calculated for cases where individuals in the social network are treated as a single information source or multiple sources. This model is tested on a social network consisting of 40 people. The results show that the strength of relations between individuals is more important to information diffusion than the number of connections individuals have. The expected energy savings of optimally chosen node can be 25.32% more than randomly chosen nodes at the end of the second month for the case of single information source in the network, and 16.96% more than random nodes for the case of multiple information sources. This illustrates that the model presented in this paper can be used to determine which individuals will have the most influence on the social network, which in turn provides a useful guide to identify targeted customers in energy efficiency technology rollout programmes.

Thermography measurements and latent heat documentation of Norwegian spruce (Picea abies) exposed to dynamic indoor climate

Hygroscopic materials hold the potential to reduce ventilation loads in a building by damping the peak fluctuations of the indoor relative humidity. Of particular interest is the moisture buffer capacity of wooden surfaces. This paper investigates, the response of Norwegian spruce (Picea abies) samples to changes of indoor relative humidity as well as the corresponding latent heat release during moisture buffering. A climate chamber was used to subject samples to dynamic air humidity. Thermographic techniques and thermocouples were employed to measure surface temperature on the exposed surface of the spruce sample (permeable case), while a covered control sample was used as reference (impermeable case). The moisture uptake was logged synchronously by weighting cells. The results show that the surface temperature of spruce increased by 2.1 °C during moisture uptake, while only by 0.9 °C in the control sample. This finding has implications for direct energy savings when wooden surfaces are used indoors. In addition, thermography is evaluated as an appropriate measurement method for documenting latent heat release.

Direct energy consumption and CO2 emissions in a Finnish broiler house – a case study

Direct energy (electricity and heating) consumption was measured from one broiler house in southern Finland. CO2 emissions were also calculated. Six broiler flocks were reared per year with an average of 26 000 birds per flock. Heating constituted the major energy input, averaging 1.3 kWh kg-1 of carcass weight. It varied greatly between seasons and was highest during the cold period. Using renewable energy for heating remarkably reduces CO2 emissions compared to fossil energy. Electricity consumption averaged 0.08 kWh kg-1 of carcass weight. The greatest energy saving potential can be found in heating. CO2 emissions can be lowered to similar levels as in warmer countries by using biofuels for heating. Ventilation control is one possibility for direct energy savings in broiler production. Feed production is one of the key elements when total energy consumption is considered.

Long-Run Backfire from Energy Policies

I study the general equilibrium implications of large-scale policies to improve energy efficiency, which are being implemented around the world to mitigate climate change. Energy efficiency policies when economic responses undercut their direct energy savings. I develop an analytic general equilibrium framework that allows improvements in energy efficiency to affect output prices and factor prices. I show that general equilibrium channels typically amplify rebound and make it more likely that improvements in efficiency end up increasing total energy use. General equilibrium channels are likely to be especially problematic when sectors targeted for efficiency improvements have a large value share of energy. In these cases, ignoring general equilibrium channels can severely bias benefit-cost analyses in favor of energy efficiency policies.

Membrane Bioreactor Process Modeling and Optimization: Ulu Pandan Water Reclamation Plant

AbstractThe operating energy efficiency of the Ulu Pandan membrane bioreactor plant is optimized by artificial neural network (ANN) and bioprocess models. The ANN model mines historical plant data to uncover optimal operating settings. Historical plant data indicate that adjusting the membrane scouring aeration cycle will lead to direct energy savings. The ANN model concurs and shows the same correlation. Changes to plant operations carry substantial risks to the stability of the plant and place limitations on the range of operational variations. A plant risk assessment is conducted to ascertain the risk proposition for the adjustment of operating parameters. The bioprocess model investigates the underlying biological treatment mechanisms to identify the impact of the solids retention time on the volatile suspended solids, soluble microbial products, and endogenous decay coefficient. Results of the modeling show qualitatively good agreement with measured operating data. The concentrations of volatile susp...