Individual Energy Use Research Articles

Turning Leaf: Eco-visualization for Mobile User Engagement

Awareness of environment trends and global warming is widespread, but personal knowledge of energy consumption is not provided in real-time or in an actionable manner to individual consumers. Using recent work in eco-visualization, an innovative mobile application has been developed, depicted with a turning leaf. The illustration of individual energy use in a mobile hand held device is designed to improve awareness while encouraging personal conservation. Additional user motivation may be present, with the turning leaf symbolizing turning over a new leaf or encouraging positive social behaviors. The mobile application is illustrated, with an analysis of the motivation and behavior which would be expected from energy-aware users.

Dynamic relationships between body size, species richness, abundance, and energy use in a shallow marine epibenthic faunal community.

We study the temporal variation in the empirical relationships among body size (S), species richness (R), and abundance (A) in a shallow marine epibenthic faunal community in Coliumo Bay, Chile. We also extend previous analyses by calculating individual energy use (E) and test whether its bivariate and trivariate relationships with S and R are in agreement with expectations derived from the energetic equivalence rule. Carnivorous and scavenger species representing over 95% of sample abundance and biomass were studied. For each individual, body size (g) was measured and E was estimated following published allometric relationships. Data for each sample were tabulated into exponential body size bins, comparing species-averaged values with individual-based estimates which allow species to potentially occupy multiple size classes. For individual-based data, both the number of individuals and species across body size classes are fit by a Weibull function rather than by a power law scaling. Species richness is also a power law of the number of individuals. Energy use shows a piecewise scaling relationship with body size, with energetic equivalence holding true only for size classes above the modal abundance class. Species-based data showed either weak linear or no significant patterns, likely due to the decrease in the number of data points across body size classes. Hence, for individual-based size spectra, the SRA relationship seems to be general despite seasonal forcing and strong disturbances in Coliumo Bay. The unimodal abundance distribution results in a piecewise energy scaling relationship, with small individuals showing a positive scaling and large individuals showing energetic equivalence. Hence, strict energetic equivalence should not be expected for unimodal abundance distributions. On the other hand, while species-based data do not show unimodal SRA relationships, energy use across body size classes did not show significant trends, supporting energetic equivalence.

Lack of energetic equivalence in forest soil invertebrates

Ecological communities consist of small abundant and large non-abundant species. The energetic equivalence rule is an often-observed pattern that could be explained by equal energy usage among abundant small organisms and non-abundant large organisms. To generate this pattern, metabolism (as an indicator of individual energy use) and abundance have to scale inversely with body mass, and cancel each other out. In contrast, the pattern referred to as biomass equivalence states that the biomass of all species in an area should be constant across the body-mass range. In this study, we investigated forest soil communities with respect to metabolism, abundance, population energy use, and biomass. We focused on four land-use types in three different landscape blocks (Biodiversity Exploratories). The soil samples contained 870 species across 12 phylogenetic groups. Our results indicated positive sublinear metabolic scaling and negative sublinear abundance scaling with species body mass. The relationships varied mainly due to differences among phylogenetic groups or feeding types, and only marginally due to land-use type. However, these scaling relationships were not exactly inverse to each other, resulting in increasing population energy use and biomass with increasing body mass for most combinations of phylogenetic group or feeding type with land-use type. Thus, our results are mostly inconsistent with the classic perception of energetic equivalence, and reject the biomass equivalence hypothesis while documenting a specific and nonrandom pattern of how abundance, energy use, and biomass are distributed across size classes. However, these patterns are consistent with two alternative predictions: the resource-thinning hypothesis, which states that abundance decreases with trophic level, and the allometric degree hypothesis, which states that population energy use should increase with population average body mass, due to correlations with the number of links of consumers and resources. Overall, our results suggest that a synthesis of food web structures with metabolic theory may be most promising for predicting natural patterns of abundance, biomass, and energy use.

Individual energy use and feedback in an office setting: A field trial

Despite national plans to deploy smart meters in small and medium businesses in the UK, there is little knowledge of occupant energy use in offices. The objectives of the study were to investigate the effect of individual feedback on energy use at the workdesk, and to test the relationship between individual determinants, energy use and energy reduction. A field trial is presented, which monitored occupant energy use and provided individual feedback to 83 office workers in a university. The trial comprised pre- and post-intervention surveys, energy measurement and provision of feedback for 18 weeks post-baseline, and two participant focus groups. The main findings were: statistically significant energy reduction was found, but not for the entire measurement period; engagement with feedback diminished over time; no measured individual variables were related to energy reduction and only attitudes to energy conservation were related to energy use; an absence of motivation to undertake energy reduction actions was in evidence. The implications for energy use in offices are considered, including the need for motivations beyond energy reduction to be harnessed to realise the clear potential for reduced energy use at workdesks.

Energy, taxonomic aggregation, and the geography of ant abundance

Ecological communities and their component populations vary geographically in abundance. Energy theory posits that abundance (the number of individuals area−1) should increase with the ratio of available energy (as net primary productivity, NPP) to individual energy use (i.e. metabolic rate). Most tests of energy theory evaluate the assumption that population abundance decreases as body mass−0.75 (a proxy of metabolic rate). Using 664 ant populations from 49 communities we examine how both NPP and body mass – individually and as a ratio – predict abundance (colonies m−2) at these different levels of taxonomic aggregation. Energy theory best predicts ant abundance when populations are aggregated into communities. At the population level, abundance formed a unimodal scatter plot vs all three drivers – colony mass, NPP, and NPP mass−0.75– suggesting that the majority of populations exist below energetic limits set by the ecosystem. At the community level, however, abundance scaled as predicted for mass−0.75 and NPP1.0, (b =−0.75 and 1.0, respectively) and was a positive decelerating function of their ratio (i.e. [NPP mass−0.75]0.61, r2= 0.68). Since geographic trends in colony mass and abundance are largely reciprocal – deserts tend to support few large colonies, and tropical rainforests support many small colonies – the geography of ant biomass (g m−2) is remarkably invariant.

Xxive Journées franco-suisses de médecine et santé au travail. Fribourg, 16–17 juin 2011. Résumés des communications

Residential resource use efficiency and management is a subject of interest to a number of fields spanning the physical and social sciences. Energy use for residential water heating in Australia is some five to eleven times more than the energy required to deliver urban water services. However, little is known about which activities within households contribute most significantly to water-related energy use (WRE). This work quantifies WRE use in individual households, and identifies household characteristics which contribute significantly to variation. Empirical data were collected through in-home audits, interviews and high-resolution end-use water flow meters for five households in Melbourne, and two in Brisbane, Australia. This was used to characterise 139 parameters describing household occupancy characteristics, behaviours, technologies, and structural and environmental aspects of influence. Mathematical material flow analysis (MMFA) modelling was conducted for individual water and energy use subsystems within each household. WRE use ranged from 7 to 21 kWh hh−1 d−1 (13–24% of total household energy use in Melbourne and 76–79% in Brisbane). Detailed end use analysis of the five Melbourne households showed that shower use (11–61% WRE), hot water system efficiency losses (8–31% WRE) and clothes washer usage (4–17% WRE) contributed most to differences in WRE between households. Findings highlighted shower use as a consistent influence on WRE across households, and suggest further investigation of shower programs as a potentially effective demand management measure for both water and energy in households. The work highlights the importance of consistent messaging for both water and energy efficiency, and suggests that a focus on both human and technical characteristics of households is needed for effective management of combined water and energy use.

Bioenergetic Constraints on Primate Abundance

Explaining variation in primate population densities is central to understanding primate ecology, evolution, and conservation. Yet no researchers to date have successfully explained variation in primate population density across dietary class and phylogeny. Most previous work has focused on measures of food availability, as access to food energy likely constrains the number of individuals supported in a given area. However, energy output may provide a measure of energy constraints on population density that does not require detailed data on food availability for a given taxon. Across mammals, many studies have shown that population densities generally scale with body mass−0.75. Because individual energy expenditures scale with body mass0.75, population energy use (the product of population density and individual energy use) does not change with body mass, which suggests the existence of energy constraints on population density across body sizes, i.e., taxa are limited to a given amount of energy use, constraining larger taxa to lower densities. We examined population energy use and individual energy expenditure in primates and tested this energy equivalence across body mass. We also used a residual analysis to remove the effects of body mass on primate population densities and energy expenditures using basal metabolic rates (BMR; kcal/d) as a proxy for total daily energy expenditure. After taking into account phylogeny, population energy use did not significantly correlate with body mass. Larger primates, which use more energy per day, live at lower population densities than smaller primates. In addition, we found a significant negative correlation between residuals of BMR from body mass and residuals of population density from body mass after taking phylogeny into account. Thus, energy costs constrain population density across a diverse sample of primates at a given body mass, and primate species that have relatively low BMRs exist at relatively high densities. A better understanding of the determinants of primate energy costs across geography and phylogeny will ultimately help us explain and predict primate population densities.

Principal component analysis and long-term building energy simulation correlation

The objective was to investigate whether energy use in buildings from simulation could be correlated with a new composite climatic index, which would account for the influences of major climatic variables such as temperature, humidity and solar radiation. Principal component analysis of prevailing weather conditions in sub-tropical Hong Kong was conducted, and a new climatic index Z determined. Multi-year (1979–2007) building energy simulations were carried out for a generic office building. It was found that Z exhibited daily and seasonal variations similar to the simulated cooling load and building energy use. Regression models were developed to correlate the simulated daily cooling load and building energy use with the corresponding daily Z. Error analysis indicated that annual building energy use from the regression models were very close to the simulated values; the difference was less than 2%. Difference in individual daily energy use, however, could be up to 6%. It was also found that both the simulated annual building energy use and the new climatic variable Z appeared to show an increasing trend during the 29-year period, indicating a subtle, but gradual change of climatic conditions that might affect energy use in buildings in future years.

Household energy use patterns and social organisation for optimal energy management in a multi-user solar energy system

Multi-user systems (MUS) for electrification of rural villages have specific advantages compared with individual systems (SHS). However, as MUS serve multiple consumers, shared energy use presents a challenging problem to the communities. Despite the increased performance of MUS over SHS, they still produce a limited amount of available energy, and users cannot consume as much electricity as they wish without considering the needs of the other users. This means that energy distribution among village residents has to be organised and energy consumption has to be controlled. There are different ways to achieve energy distribution. One possibility is to leave it to the users themselves to organise rational energy use according to their needs and daily routines. For the development of a self-managed scheme, knowledge is required not only of the users' total energy consumption, but also of their individual energy use patterns. With knowledge of the community's energy consumption habits, rules for adequate energy use can be developed more accurately. The present study describes community energy management in a Cuban village using a central photovoltaic installation. Applying different methods, data were collected in order to identify individual energy use patterns and to investigate how villagers distribute energy and what rules of use are in effect. We wanted to find out whether their energy management leads to well-adapted energy use patterns and reasonable system performance. The results show that the village residents have developed rules and agreements for coordination of their energy use that have led to good adaptation to the dynamics of energy production. Copyright © 2006 John Wiley & Sons, Ltd.

Motivating Residents to Conserve Energy without Financial Incentives

Given the aim to motivate people to conserve energy in homes, we need to understand what drives people’s energy use behavior and how it can be influenced. This article describes applied energy conservation campaigns at two U.S. military installations where residents do not pay their own utility bills. Customized approaches were designed for each installation based on a broad social-psychological model. Before-and-after energy use was measured, and residents were surveyed about end use behaviors. Residents said they were motivated by the desire to do the right thing, set good examples for their children, and have comfortable homes. For sustained change, respondents recommended continued awareness and education, disincentives, and incentives. Findings support some aspects of a social-psychological model, with emphasis on altruistic and egoistic motives for behavioral change. These studies may have implications for situations where residents are not billed for individual energy use, including other government-subsidized facilities, master-metered apartments, and university dormitories.

Body Size and Density: The Limits to Biomass and Energy Use

Large scale patterns in animal assemblages are increasingly being used as a method of understanding how species abundances in such assemblages are determined (see Lawton 1989, 1991, for reviews). In particular, the relationship between species abundance, measured as density or number of individuals, and species body size has received considerable interest (Brown and Maurer 1987, Gaston 1988, Morse et al. 1988, Tokeshi 1990, Basset and Kitching 1991, Nee et al. 1991, Griffiths 1992, Novotny 1992, Blackburn et al. 1993, Currie 1993). Much less attention has been given to other measures of abundance across animal assemblages, such as the distributions of biomass and energy use across species. One notable exception is a study of a bird assemblage by Maurer and Brown (1988). Maurer and Brown showed how biomass and energy use were distributed across 380 species of North American terrestrial birds, using literature data on body size, population density and individual energy use. When biomass and population energy use are plotted against mean body weight for individual species on log-log axes, values for individual species fall within well defined tetrahedra (Figs 3 and 4 in Maurer and Brown 1988, reproduced as Fig. la,b here; see also discussion on p. 1927 of Maurer and Brown 1988). The upper boundaries of these tetrahedra, representing maximum species biomass and energy use for each body size, increase linearly up to a weight of about 60 g, before levelling off. The lower boundaries increase linearly across the whole body size range, with slopes of approximately 1.0 and 0.67 for the biomass and energy use graphs respectively. The left hand boundary of each tetrahedron is determined by the variation in abundances of the very smallest species in the assemblage, but what constrains the upper and lower boundaries is not obvious, and Maurer and Brown (1988: 1930) suggest that defining these constraints should be a focus of future macro-ecological research. We agree wholeheartedly with the aim of using macroecological patterns in assemblages to understand species abundances. We would, however, draw attention to explanations for both the lower and upper boundaries of the two tetrahedra which suggest that the biomass and energy use distributions are artefacts of the abundance data from which the species biomass and energy use values were calculated. Some account of these artefacts will be needed in future considerations of these distributions. The explanations presented are partly extensions of previously published observations on possible artefacts in assemblage patterns (Blackburn et al. 1990), and apply to the patterns in biomass and energy use in identical fashion. We deal with the lower boundary first. Maurer and Brown calculated species biomass, B, for each bird species as B = M-D, where M is the mean body weight of individuals of the species, and D is the species density. The density data were taken from the Breeding Bird Surveys (BBS) conducted by the US and Canadian Fish and Wildlife Services, for which birds are counted over a large number of standard transect routes. They were calculated as the average species density per route on which the species was recorded. Since the minimum density a bird species can have in the BBS data is 1.0 individual/route, the minimum value for B is M, when D = 1.0. Thus for the plot of log species biomass against log body size, species points cannot lie below the line with slope 1.0 and intercept at the origin (when B = M. 1.0, or logB = logM+ logl.0 = logM). Since the bird assemblage used by Maurer and Brown includes species of density 1.0 across a wide range of body sizes (Brown and Maurer 1987), this slope indeed approximates 1.0 (Maurer and Brown 1988: Fig. 3).

The Thermal Physiology of the Feathertail Glider, Acrobates Pygmaeus (Marsupialia:Burramyidae).

Feathertail gliders are small arboreal marsupials from south-eastern Australia. Laboratory studies found that body temperature was labile and varied by 3.5�C throughout the day. Body temperature (Tb) control was stricter at low ambient temperature (Ta). Within the narrow thermal neutral zone (TNZ, 34.0-35.1�C), the basal metabolic rate was 2.11 W kg-0.75 (mean body mass 14.0 g) which is 13% lower than expected for a marsupial. Mass specific thermal conductance decreased with T, and the fleshy gliding membranes did not appear to contribute to the insulation. Huddling in groups of four or eight significantly reduced an individual's energy use. During torpor, Tb fell to close to Ta, the lowest Tb being 6.9�C, but torpor rarely lasted longer than 24 h. Groups of feathertail gliders often became torpid and showed a similar pattern of oxygen use during torpor to that seen in individuals. Some groups contained both torpid and normothermic individuals. This situation may benefit the torpid animals by reducing the cost of arousal and increasing the rate of rewarming.

From social psychology to political economy: A model of energy use behavior

Multiple and complex factors determine people's energy use behavior. However, policies designed to affect individual energy use behavior focus mostly on a limited number of micro, short-run and easily manipulable variables. These have produced limited response. A theoretical framework is proposed in this paper that attempts to provide a comprehensive and integrative view of energy use behavior. The framework examines variables that create and maintain particular types and intensities of energy use behavior. Based on this framework, implications for energy policies and their potential effectiveness have been drawn.