• Energy Research
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Abstract The concept of Zero Energy Building (ZEB) has gained wide international attention during last few years and is now seen as the future target for the design of buildings. However, before being fully implemented in the national building codes and international standards, the ZEB concept requires clear and consistent definition and a commonly agreed energy calculation methodology. The most important issues that should be given special attention before developing a new ZEB definition are: (1) the metric of the balance, (2) the balancing period, (3) the type of energy use included in the balance, (4) the type of energy balance, (5) the accepted renewable energy supply options, (6) the connection to the energy infrastructure and (7) the requirements for the energy efficiency, the indoor climate and in case of gird connected ZEB for the building–grid interaction. This paper focuses on the review of the most of the existing ZEB definitions and the various approaches towards possible ZEB calculation methodologies. It presents and discusses possible answers to the abovementioned issues in order to facilitate the development of a consistent ZEB definition and a robust energy calculation methodology.

Abstract This article presents a model of natural ventilation of buildings at the stage of design and a consequence of the behaviour of the occupants. An evaluation is made by coupling multizone air modelling and thermal building simulation using a deterministic set of input factors comprising among others climate, local environment, building characteristics, building systems, behaviour of occupants and heat loads. Selected deterministic input factors are varied to generate additional information applied in an optimization loop. With that, it is found that the optimal solution depends to a great extent on the possibility of optimization of the behaviour of occupants, and to a lesser extent on the design of the building.

The existing building stock requires substantial interventions to meet the energy performance criteria imposed by the current standards. The installation of a new insulating layer into the building envelope is the most common energy retrofit measure. This strategy is usually focused only on steady state thermal conditions while it influences also the transient thermal behavior. However the on - site characterization of the building dynamic behavior is partially or totally neglected, due to the lack of a feasible investigation procedure. This may lead to a negative thermal performance of the building, paving the way to litigations between the contractor and the tenants. A novel measurement technique, based on infrared thermography, is proposed to investigate the dynamic behavior of the wall. Several wall samples are tested in laboratory with an experimental layout that resembled an outdoor installation, where a sinusoidal thermal stimulus is imposed on the back of the specimen. The surface temperature evolution over time is recorded with an infrared camera both on the front and on the back surfaces of the specimen, in order to measure the time-shift on a broad wall area. A key aspect of the proposed experimental procedure is that it could be applied to the on-site building survey, significantly improving the evaluation of the actual energy performance of the building. The obtained results are compared with a mathematical model showing good agreement.

Abstract The reduction of the energy consumption and carbon emissions in the building sector is an important target for actions to mitigate the climate changes and different actions are being carried out to promote a transition to a low carbon built environment. However, present standards are mainly focused on new buildings which may result counter-productive in existing ones, due to their technical, functional and economic constraints. One of the most common problems in the current way of assessing building renovation scenarios is that only energy savings and cost are considered, disregarding additional benefits. Many studies, based on real cases, have already highlighted the relevance of these so-called co-benefits, which can be felt at the building level (and therefore they should be considered in the definition of the renovation measures) and also at the level of society. The present investigation has been developed under the scope of IEA EBC Annex 56 project, and a method to integrate co-benefits in the evaluation of the renovation scenarios towards both the nearly-zero emissions and the nearly-zero energy objectives is proposed. It has been applied to case-studies from several European countries and based on subsequent findings recommendations for policy makers and professional owners are presented.

Abstract Public school buildings represent an important share of public buildings in Europe, some of them built several decades ago. In Portugal, there are about 5800 public schools, many of them in free-running conditions, with significant thermal discomfort and without any heating strategy due to economic restrictions. This work studies the Portuguese Brandao school model (from the ‘70 s), which comprises about 100 non-refurbished basic schools. This paper suggests the passive refurbishment of these public schools with some affordable interventions, regarding the climate features and the reduced capacity to support the operating costs. A prototype classroom was prepared in a Brandao school, in Porto. The in situ experimental campaign consisted of temperature, relative humidity, CO2 concentration and energy consumption measurements. The prototype construction included the improvement of the envelope and of the technical systems. The main goals of this work are: (1) the comparison of the prototype in-service thermal performance in pre-existing conditions and the improvement after the refurbishment in free-running conditions or with some intermittent heating strategies; (2) the establishment of discomfort indexes for the assessment of the discomfort for Mediterranean temperate climate; (3) the quantification of the energy consumption vs discomfort regarding the passive refurbishment strategy and the intermittent heating strategies. When comparing the before and after refurbishment results, the mean daily discomfort indicator has decreased from 34.7 °C.hour to 25.2 °C.hour in free-running conditions and after the refurbishment has decreased from 25.2 °C.hour to 11.9 °C.hour for 3 heating hours strategy and to 2.5 °C.hour for 10 heating hours strategy. There was an expected increase of CO2 inside the classroom for the corresponding months before and after refurbishment, although the mean CO2 was below the required 1500 ppm.

This paper takes an overall energy system approach to analysing the mismatch problem of zero energy and zero emission buildings (ZEBs). The mismatch arises from hourly differences in energy production and consumption at the building level and results in the need for exchange of electricity via the public grid even though the building has an annual net-exchange of zero. This paper argues that, when looked upon from the viewpoint of the overall electricity supply system, a mismatch can be both negative and positive. Moreover, there are often both an element of levelling out mismatches between individual buildings and an element of economy of scale. For these three reasons mismatches should be dealt with at the aggregated level and not at the individual level of each building. Instead, this paper suggests to compensate the mismatch of a building by increasing (or decreasing) the capacity of the energy production unit. Based on historical data for the electricity supply area in western Denmark, this paper makes a first attempt to quantify mismatch compensation factors. The results indicate that such compensation factors are a little below one for buildings with photovoltaics (PV) and a little above one for buildings with wind turbines.

Abstract Since children are far more vulnerable than adults to the effects of air pollution and spend about a third of their day in school, strict control of indoor environments in educational buildings is paramount to properly identify, manage and mitigate putative environmental risks for children. In this context, this work aimed to provide a holistic view on the outcomes obtained from the national ARIA project, which was focused on broadening the knowledge on the effects on children’s health of the exposure to schools’ indoor air. In particular, this work performed a comprehensive investigation of the indoor air quality (IAQ) in 20 public primary schools located in Porto (Northern Region, Portugal). This paper presents the results of the investigation along with the recently published main outcomes of ARIA on (1) the characteristics of the environment surrounding the surveyed buildings, and (2) the school’s environment-related health effects in school-age children from the studied classrooms. The investigation consisted in an extensive assessment plan conducted in 71 classrooms to assess temperature, relative humidity, carbon monoxide and dioxide, particulate matter (PM2.5, PM10, and ultrafine particles), nitrogen dioxide, ozone, volatile organic compounds, formaldehyde, acetaldehyde, airborne fungi, bacteria and endotoxins, and investigate their respective sources, during the cold seasons of 2014–2015. A series of studies was also launched to investigate school environment-related health detriments in 916 children. The results showed that comfort and ventilation issues and/or indoor pollutant levels that exceeded recommended limits were found in a substantial number of the classrooms surveyed. The high density of occupants, deficient ventilation, soil characteristics, presence of indoor pollution sources (e.g. classroom materials and consumer products) and outdoor pollution were some of the factors that seemed to explain the high air stuffiness and/or indoor pollution load identified in classrooms. In fact, some of indoor pollutants detected, even at low exposure levels, were associated with the development of respiratory symptoms in school-age children. Moreover, results from this work have also shown that the characteristics of the environment surrounding the schools, namely the presence of green spaces and species richness, can be major determinants of respiratory health among school-age children. Overall, the body of evidence generated from the ARIA project can support new evidence-based perspectives for promotion of health in educational buildings.

Abstract With the ageing of population in Europe, the housing stock needs to meet the demands of older occupants, including an increasing demand for energy efficiency. As collective entities, Dutch social housing associations are among the frontrunners in achieving the energy and comfort goals of the European Union and the national government. This paper presents a number of case studies from the domain of social housing for older people from The Netherlands. The cases presented focus on the baseline conditions, the interventions conducted, the financial aspects and the involvement of stakeholders. Implications and recommendations for the design and retrofitting of housing, as well as the process of improving energy efficiency and comfort in practice, are discussed on a supranational level.