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Residential and service (office) buildings consume a large proportion of primary energy in Europe in the form of electricity and all other energy carriers. In response to this, the concept of near Zero Energy Buildings (nZEB) has been developed. These buildings have very low energy demands and integrate renewable energy to supply residual demand. nZEBs aim to increase energy efficiency from a demand-side user perspective. When looking at the entire energy system, there are also energy efficiency gains to be achieved on the supply-side. For example, from a district heating system. If an energy system becomes more efficient on the supply-side, then the question is how much energy needs to be saved on the demand-side, for instance by low energy buildings such as nZEBs. The purpose of this paper is to analyse and understand the implications from building new low energy buildings, i.e. nZEBs, within an energy system that is (a) transitioning to 100% renewable energy and (b) has substantially improved supply-side energy efficiency. A case study from Denmark is used to understand the outcome for the energy system when these new buildings are built in this context. The methodology and results of this study could be replicated for other European countries as well. The analysis looks at the total energy system heat savings, costs and biomass consumption. The paper shows that these new low energy buildings with very low heat demand do not deliver the expected benefits for the 100% renewable energy system transition in Denmark. This is due to the increased efficiency and flexibility of the energy supply system in the future. However, deep renovations of existing buildings are necessary. Furthermore, this paper demonstrates based on the Danish case, that as European countries decarbonise their energy systems over the next decades, they will need to carry out detailed energy system analysis to determine the extent to which heat demand should be reduced in buildings within the context of the transitioning energy system. [ABSTRACT FROM AUTHOR]

Building retrofits are strongly dependent on the individual refurbishment/rehabilitation cycles of buildings. In order to achieve the targeted climate goals for the building sector, it is necessary to make the best possible use of refurbishment opportunities for energy retrofits. Furthermore, it must be considered that the younger the building, the lower the potential for energy savings. The most challenging, yet required, energy retrofits are all yet to come. Given the importance of the refurbishment cycle, the question arises as to what the theoretical refurbishment rate is, what the actual energy retrofit rate is, and what it needs to be in order to meet the climate targets for the residential building stock. The aim of this paper is to model the evolution of the size and retrofit status of national building stocks. This is to be done against the background of the deviation from the actual and theoretical refurbishment cycle. Using current statistics and the past development of the German residential building stock, central parameters like living space, new construction, deconstruction, and the retrofit rate are modeled endogenously. For the latter, influences of economic conditions are implemented through an exogenously set black box variable. The retrofit rate represents a deep energy retrofit and thus allows an easy connection of the model with energy parameters for building classes defined in the web database TABULA for 20 European countries. The results are of relevance for modeling the energy efficiency status of the building stock and deriving suitable conditions for increasing retrofit rates also in other countries. The results show that increasing the energy retrofit rates to 2%/a or more is largely unrealistic. Instead, the focus should be on weak points, especially where short-term savings are concerned. This applies in particular to facades, basement ceilings, and heating systems as well as the efficient use of energy in buildings. [ABSTRACT FROM AUTHOR]

Existing buildings represent a significant energy saving potential in Europe, and retrofitting the building stock is essential to reach European targets. Retrofitting measures should reduce the energy consumption as well as improve the indoor climate while still being cost-effective. This can be challenging in European cold climates. This paper discusses energy performance requirements and challenges in the retrofitting process. It also presents an overview of the retrofitting status and relevant energy saving retrofitting measures with their potential for residential buildings. Measures to lower the building's energy demand and electrical energy consumption and measures to control and monitor the energy use are discussed. Some research directions for the future of building energy usage are suggested. The literature indicates that significant energy savings can be achieved from retrofitting the building envelope. Relatively few research papers have been devoted to the energy saving potential of building control systems for existing residential buildings. However, these savings seem low compared to those that can be achieved through energy conservation. The actual savings from retrofitting the envelope, HVAC-systems and control systems are case specific and should be assessed for reference buildings of each housing typology. [ABSTRACT FROM AUTHOR]

Energy renovations offer unique opportunities to increase the energy efficiency of the built environment and for the existing housing stock; they are the most important solution. Usually, energy savings are based on modeling calculations. However, recent research has shown that the predicted energy consumption differs largely from the actual consumption. In this paper, the effectiveness of energy measures is re-assessed based on actual consumption data. We use a monitoring system, which contains information about the energy performance of around 60% of the Dutch non-profit housing sector (circa 1.2 million dwellings). We connect the data from this monitoring system to actual energy consumption data from Statistics Netherlands on a dwelling level. Using longitudinal analysis methods, from 2010 to 2014, we are able to identify the energy efficiency improvements of the stock and determine the effectiveness of different measures in terms of actual energy savings. The results reveal the actual energy savings of different efficiency measures and highlight the significance of the actual energy consumption when a renovation is planned or realized. [ABSTRACT FROM AUTHOR]

Energy retrofitting of existing buildings is a central challenge for local, national, and international climate policies, and in several countries, single-family houses represent a major energy-saving potential. Although many municipalities are implementing local climate policies with initiatives to promote energy retrofitting of buildings, little research has been done regarding the role of single-family houses in local climate policies. Thus, we have little knowledge about specific initiatives to promote energy retrofitting amongst owners of single-family houses, we know little about experience from such initiatives, and we lack knowledge about the extent to which national and EU policies support local initiatives directed at homeowners. This article provides insights into these issues from an explorative study on local climate strategies in Danish front-runner municipalities where single-family housing is the dominating building segment. Based on a study of local governance strategies in 12 municipalities targeting homeowners' engagement in energy retrofitting, the paper finds that these municipalities have developed promising local network-based ways to engage homeowners in energy retrofitting, but finds simultaneously that the national policy mix is only partly supporting these local initiatives. The paper also points out that the local and regional context for the programmes, including the local economic situation, is of great importance, and this context creates both potentials and challenges for the local programmes. [ABSTRACT FROM AUTHOR]

The Passive House (PH) standard is a voluntary quality assurance standard focused upon maximising the health and wellbeing of occupants, whilst reducing space heating demand to a very low level. To meet the PH standard, well-defined criteria have to be met. However, given literature that suggests a 'performance gap' for energy savings, the question remains, how well do PH dwellings perform in situ? This paper presents results from in situ building fabric thermal performance measurements, along with a comparison between the design intent and the measured space heating energy used by over 2000 newly built and retrofitted PH dwellings. The results reveal the in situ thermal performance of the building fabric is close to the design predictions. Within space heating measurements, a standard deviation of up to 50% has to be attributed to the broad spectrum of user behaviour; this is not specific for PH, but a general observation. Despite this, the average values for the PH developments ranged within the uncertainty of the demand calculations. With over 2000 PH dwellings averaging a space heating energy consumption of 14.6 kWh/(m2a), the in situ performance is close to the original design intent and extraordinary low compared to the consumption in ordinary buildings. The results suggest the PH standard is capable of producing dwellings in a verifiable manner. This means, on average, the in situ thermal performance of the building fabric and the energy consumption for space heating match the design intent, i.e. there is no significant 'performance gap'. [ABSTRACT FROM AUTHOR]

To test the effectiveness of a competitive or collaborative approach on engaging people to change their household electricity-use habits, a mobile app, called Social Power, is developed to provide electricity meter feedback in two gamified environments. The project aims at stimulating social engagement and promoting behavioral change to save electricity at the household level by forming teams of neighbors in two Swiss cities. The household participants are assigned to one of two teams: either a collaborative team where citizens in the same city try to reach a fixed, 10% electricity savings target collectively or a competitive team which tries to save the most electricity in comparison to another city. The collaborative and competitive gamified structures are run in parallel as a 3-month field experiment (February to May 2016) involving 108 recruited household participants in two cities, with ultimately 46 who actively play. In this paper, we present the result of the two gamified structures on the sustainability of reported behavior, as well as on actual saved electricity. Overall, a collaborative or a competitive intervention contributes to electricity savings and reported behavior as compared to the control group; however, no significant difference is found between the two gamified structures. [ABSTRACT FROM AUTHOR]

This paper presents an approach proposed for assessing economic performance of retrofit applications performed at functional building element level in residential buildings and exemplifies it for the city of Istanbul, which has a temperate-humid climate. This approach covers three steps. In the first step, typical buildings and their properties are determined by analysing the residential buildings in Istanbul, and then the retrofit alternatives are generated. In the second step, an economic impact analysis is performed for typical buildings by considering the costs during their life cycle phases. In the third step, a life cycle cost assessment is done according to the variables, which are defined as window-to-wall ratio (WWR), window system, thermal insulation material, orientation and building age. The most beneficial retrofits are lastly determined depending on their economic performance ratios (EPRs). In conclusion, insulating exterior wall, projected floors, floors above unheated space and roof floors separately provide the highest benefits at the age of 30, and the lowest benefits occur at the age of 15 for all WWRs. The highest EPRs are obtained for the WWR of 10% at all ages. The renewal with PVC frame provides benefit while the renewal with wooden frame causes losses. Orientation slightly affects the EPRs. The use of stone wool in the retrofit causes a reduction in the EPRs due to high investment cost of stone wool. When the 20-year-old building which has the WWR of 10% is insulated with extruded polystyrene and renewed with PVC, it provides the highest benefit of about 45%. [ABSTRACT FROM AUTHOR]

The residential building stock holds a large energy efficiency improvement potential related to energy upgrading of the building envelope. Details about the heterogeneity of the building stock are paramount to perform a proper assessment of attractive energy efficiency improvements for end-users. Based on a sample of buildings, the study develops methods to identify potentials for heterogeneous building-tailored energy efficiency improvements, to reduce heat consumption, and evaluates their cost-effectiveness in the framework of a district heating area in Denmark. The study accounts for rebound effects and develops both technical (gross) and more realistic (net) potentials, allowing a more accurate analysis of attractive energy efficiency improvements. The analysis is novel as the underlying model relies on building characteristics rather than synthetic archetypes, which can lead to loss of diversity (e.g. in variation of costs and potentials) and thereby discarding cost-effective potentials. The analysis also investigates the sensitivity of the results to assumptions about the discount rate and focuses on the effect of exposing the end-user to different district heating tariffs and the consequent total cost-effective investments. The outcomes show that cost-effective energy efficiency improvements vary considerably, in size and type, among the heterogeneous building stock considered. In regard to district heating tariffs, when all the cost components are variable, the total cost-effective potential increases considerably, with specific energy efficiency improvements distributed differently among building categories, and with the cost components providing different incentives to invest. Heterogeneity, and different tariff policies, thus does matter, when evaluating economically attractive investments in energy efficiency improvements for buildings. [ABSTRACT FROM AUTHOR]

Consumption patterns of residential building in Kingdom of Saudi Arabia (KSA) with specific reference to Qassim region are analysed to establish energy consumption indicators including consumption per dwelling, per capita and per unit area. The average shares of lighting, domestic appliances, water heaters and air conditioning out of total yearly consumption are determined to be 8.5%, 14.7%, 10.3% and 66.5%, respectively. Parametric analysis shows that residential energy consumption is insignificantly influenced by the type of building except that villas have somewhat higher consumption during the hot summer season. However, residential energy consumption is considerably affected by occupant behaviour, meteorological conditions, as well as the technical conditions of both building envelopes and air conditions setting temperature point. Energy efficiency measures are also discussed, and opportunities for energy saving are proposed. Potential energy savings up to 43% in air conditioning cooling load could be achieved by applying the KSA standard of envelope insulation. Total residential consumption savings of 3% could also be achieved by using efficient lighting and savings of 11.1% by adjusting the temperature setting point of air conditioners to 24 °C instead of 22 °C. [ABSTRACT FROM AUTHOR]

Cost-effective energy efficiency improvements in residential buildings can realize 30% energy reduction within this energy sector for the USA. Unfortunately, audits on residences to identify potential savings, generally based on detailed energy models, tend to over-estimate anticipated savings. This leads to wariness on the part of potential investors. We address this issue by taking an integrated data- and physics-based approach, using residential building geometrical and energy system characteristics (e.g., envelope, appliances, and HVAC systems), as well as historical energy consumption for each residence and weather data, to predict monthly natural gas energy consumption and savings from the adoption of individual energy saving measures. This approach requires only those geometrical and energy system characteristics associated with the greatest potential for realized savings which are also easy to obtain. We construct a dataset from a collection of houses with a wide range of energy effectiveness, and train a single statistical model that accurately predicts natural gas energy consumption in any of the individual residences. The model is then used to estimate the savings from most impactful energy efficiency investments for individual residences, as well as the collective grouping. The specific case considered here involves hundreds of university-owned student residences in the U.S. Midwest. The resulting machine-learning derived model is used to predict monthly natural gas consumption with a mean squared error of 0.00023 for unitary scaled cross-validation data. We use a nearest neighbor approach to validate savings estimates for virtually improved residences, identifying the surrogate residence most like an improved residence. This validation demonstrates a savings prediction accuracy to within 3.5% for most of the measures considered. The validated models are shown capable of prioritizing investments among the collective of residences considered. Sequential adoption of the most cost-effective energy efficiency measure among a group of residences renders a total energy reduction of 36%. The practical implications of this research are significant. This integrated machine-learning and physics-based approach to estimate savings could be used in any utility district and throughout all of the USA to enable district-wide residential energy reduction based upon sequential adoption of the most cost-effective energy measures. [ABSTRACT FROM AUTHOR]

In public debate, Energy Performance Certificates (EPCs) of buildings have been criticised for not reflecting the energy demand realistically. And indeed, measurement, as in energy bills, usually differs from the calculation, in particular, when simplified energy performance calculation models and standard specifications are applied, as in EPCs. Thus, energy-saving potentials of refurbishment recommendations and their cost-effectiveness tend to be over-estimated. Of course, this is not desirable. These effects were analysed in two sets of data, the Energy Performance Certificate Register for residential buildings in Luxemburg, run by the Luxemburg Ministry of the Economy (Lichtmeß, 2012) and a database gathered in the research project "Teilenergiekennwerte von Nichtwohngebäuden (TEK)" (Hörner et al., 2014a) funded by the German Federal Ministry of Economic Affairs and Energy. Multiple linear regression and error calculus were applied to study the gap between measurement and various calculation models in detail. A statistical procedure is proposed to estimate expectation value and variance of the future energy consumption of buildings in case of refurbishment, as a supplement to standard calculations in EPCs for example. Prerequisite is that for a sufficient number of buildings, data on both, measured energy consumption and calculated demand, are available. [ABSTRACT FROM AUTHOR]

This research examines some of the multiple benefits of a home energy efficiency upgrade programme for social housing tenants. Employing a quasi-experimental approach, we examine a range of objectively measured and self-reported outcomes, including metered gas consumption, for a control and upgrade group, before and after the upgrade. We drew our sample from a large home energy efficiency programme in Ireland, The SEAI Better Energy Communities Scheme, which provides funding for whole communities to upgrade the efficiency of their dwellings. Dwellings were selected for upgrade based on need, allowing us to control for observable dwelling characteristics correlated with selection into the trial. The upgrades undertaken were extensive relative to the average home energy improvement, with many dwellings receiving a number of measures. Households reported improvements across a range of outcomes associated with heating-related deprivation and comfort in the home. We use panel regression models to estimate the elasticity of gas demand with respect to the thermal efficiency of the dwellings. Overall, we find that use of natural gas fell much less than 1:1 for each increment to thermal efficiency of the home. For the average household in this study, about one third of the marginal increase in thermal efficiency was reflected in reduced gas demand. This result highlights issues with standard engineering models which are commonly used to assess the energy efficiency of dwellings and points to a behavioural response from households, potentially taking back some of the savings as increased internal temperatures. [ABSTRACT FROM AUTHOR]

Throughout the developed world, residential buildings in the rental sector exhibit lower levels of energy efficiency than the owner-occupied building stock. This study estimates Irish rental tenants' willingness-to-pay for energy efficiency improvements. A double-bounded dichotomous choice contingent valuation method is used to examine how much renters are willing to pay in their monthly rent for improved energy efficiency, measured via energy performance certificates. Using an administrative dataset from a grant scheme for residential energy efficiency retrofits, we examine the upfront cost to landlords of engaging in energy efficiency retrofits and calculate associated payback periods. Tenants in Ireland are willing to pay an average of €38 for a one-grade improvement along a 15-point energy performance certificate scale. Providing additional information about energy performance certificates and the potential impact on energy costs reduced mean willingness-to-pay, implying that in the absence of information tenants overvalued energy efficiency labels. Based on tenants' willingness-to-pay, investment payback periods for attic and cavity wall insulation are relatively short but prohibitively long for external wall insulation and solar heating retrofits. [ABSTRACT FROM AUTHOR]

Regional energy efficiency programmes are of particular interest as they tackle local constraints which are not always targeted by national energy policy. Within this framework, an energy efficiency programme for existing dwellings has been implemented in a southern European region, providing financial incentives for a combination of energy efficiency actions (heat pump combined with insulation and/or solar water heater). Ex-post evaluation results of this pilot programme are reported in this study. More than 200 households were surveyed regarding their individual energy consumption as well as house and household characteristics. Likewise, the survey highlights household behaviours concerning both space heating and air conditioning, before and after refurbishment. A 3-year billing analysis is used to calculate the energy savings attributed to the operation. Evaluations are carried out taking into account critical parameters like climate differences between years or direct (enhanced space heating comfort) and indirect (use of air conditioning) rebound effects via a statistical model. Moreover, an uncertainty assessment of energy savings was realized on the basis of three scenarios (low, median and high). This study is particularly focused on the use of air conditioning by households, data rarely found in the literature, whereas the consumption linked to air conditioning should increase in the residential sector especially in southern regions. These results help in answering questions about the installation of heat pumps in existing single-family houses with respect to energy savings as well as direct and indirect rebound effects. [ABSTRACT FROM AUTHOR]

There has been an increased in attention placed on the energy consumption of miscellaneous electronic loads in buildings by energy analysts and policymakers in recent years. The share of electricity consumed by consumer electronics in US households has increased in the last decade. Many devices, however, lack robust energy use data, making energy consumption estimates difficult and uncertain. Video game consoles are high-performance machines present in approximately half of all households and can consume a considerable amount of power. The precise usage of game consoles has significant uncertainty, however, leading to a wide range of recent national energy consumption estimates. We present here an analysis based on field-metered usage data, collected as part of a larger field metering study in the USA. This larger study collected data from 880 households in 2012 on a variety of devices, including 113 game consoles (the majority of which are Generation 7 consoles). From our metering, we find that although some consoles are left on nearly 24 h/day, the overall average usage is lower than many other studies have assumed, leading to a US national energy consumption estimate of 7.1 TWh in 2012. Nevertheless, there is an opportunity to reduce energy use with proper game console power management, as a substantial amount of game console usage occurs with the television turned off. The emergence of Generation 8 consoles may increase national energy consumption. [ABSTRACT FROM AUTHOR]

Energy consumption baselines are essential in promoting energy efficiency programs in an effort to mitigate the environmental impacts of increasing consumption and increasing home sizes. This study calculates baselines, using site and source energy index (EI), of approximately 348,000 detached single-family homes in San Antonio, Texas to facilitate energy efficiency programs. The data analysis pairs building characteristics of individual houses with their energy consumption, allowing researchers to categorically study houses based on EI, vintage (year built), conditioned space (size), and type of fuel and energy utilized. This study found that the size of single-family detached houses has increased over time, while average site and source energy index values have decreased. The majority of single-family detached houses (45.8 % of total or 159,147 houses) have an energy index of 25-50 kBtu/sf/year (78.8-157.7 kWh/m/year). The majority of all-electric single-family detached houses have been built since 1980, resulting in better performance than anticipated when compared with houses having access to natural gas. Most homes built after 1990 are distributed in the lower (more efficient) energy index categories, indicating that energy efficiency programs for newer, larger houses should be behavioral or educational in nature while programs for older houses should improve the infrastructure. [ABSTRACT FROM AUTHOR]