Agis M. Papadopoulos

Feasibility of energy saving renovation measures in urban buildings: The impact of energy prices and the acceptable pay back time criterion

Abstract The energy renovation of existing buildings is an important tool for the reduction of energy consumption in the building sector, the improvement of prevailing indoor thermal comfort conditions and also for the improvement of environmental conditions in urban areas. At the same time, it is a technical, economic and social problem, due to the way in which many cities have been built and the restrictions imposed by economic constrains that tantalise most countries in South-Eastern Europe, and also Greece. It applies particularly in Northern Greece, with its cold and prolonged heating season, where a series of studies was carried out since 1994 to approach the problem and develop viable proposals. Public and mixed-use buildings form a significant part of the building stock and are therefore a primary candidate for energy saving measures, especially as they also play the role of a ‘pilot-demonstrator’ for the private owned buildings. However, due to the low energy prices that prevailed over the last 10 years, and as energy saving measurements are capital intensive investments, little was done in that direction. The recent sharp increase in oil prices proved that this was a short-sighted policy. In the following paper are presented the results of a study that aimed to determine the potential of energy saving renovation measures, in a representative sample of buildings under realistic conditions, to evaluate the feasibility of these measures, and also the way in which this feasibility is being analysed, under the rapidly changing economic conditions.

Perspectives of solar cooling in view of the developments in the air-conditioning sector

Changes in the standards of thermal comfort in the urban microclimate and in the capital cost of air-conditioning equipment have drastically increased the energy consumption in the building sector over the last decade. At the same time, the integration of renewable energy systems, mainly active solar ones, in buildings has been an area of intense research over the last 30 years. This has also been the case in the field of solar refrigeration, mainly in the field of sorption systems. The analysis discussed in the paper is focused on the state of the art of thermal solar systems use and on the possibilities of combining those with state of the art technologies in sorption refrigeration, in order to cover the cooling demand of residential and commercial buildings. This was done by assessing the available solar and refrigeration technologies as well as by highlighting the situation in the building market, as this is still the dominant factor for the propagation of such systems.

The influence of street canyons on the cooling loads of buildings and the performance of air conditioning systems

The impact of microclimatic conditions in urban areas on the thermal loads of buildings has been appreciated fairly recently. The modulation of street canyons has led, inter alia, to temperature conditions that depart from the climatic data monitored at meteorological stations, affecting the heating balance of buildings, while the building operation affects the present conditions. The installation of air conditioning units leads to heat emission, which, at a microscale level, strengthens this phenomenon. The present paper outlines a computational approach to the street canyon phenomenon, with the determination of flow and temperature fields which are developed, and discusses their influence on the dynamic thermal balance of the building.

Energy study of a medieval tower, restored as a museum

Museums are buildings of particular significance due to their function and their status. At the same time they are buildings in which the principles of energy conservation are rarely applied, sometimes without reason. It has been decided by the Hellenic Ministry of Culture to convert a medieval tower, built in the year 1344 as a fortress with 0.8–1.5 m thick walls and almost no windows, into a museum. The present paper discusses the difficulties that arise in the attempt to balance between the indoor climate conditions necessary to protect the exhibits and to provide comfortable conditions to the visitors, whilst respecting the aesthetics and the historical significance of the building. Furthermore, one needs to consider the difficult but necessary task of assessing factors such as the building’s shell’s thermal conductivity and capacity, the ventilation necessary as well as the indoor air movement, in order to determine the cooling loads. Finally, the challenge lies in designing and dimensioning an effective and efficient HVAC system, which should be as discrete as possible. The present paper aims to present the results of the study, to discuss the expected energy behaviour of the building and to comment on the options for introducing energy conservation techniques.

Energy Cost and its Impact on Regulating Building Energy Behaviour

Abstract The need to improve building energy behaviour was born out of the price shock caused by the oil crises in the 1970s. The response was expressed by national legislative acts regulating the demand for heating and ventilation. The results were important, though not always without side effects, for example, in the field of indoor air quality. Furthermore, economic and environmental considerations played an important role in determining the policies applied, the latter particularly in the 1990s and as a result of the Kyoto and Montreal Protocols. Finally, new problems, like the increasing demand for air conditioning and its impact on national electricity systems began to influence the way in which a buildings energy behaviour is considered. The enforcement of the European Directive on the Energy Performance of Buildings (2002/91/EC) seems to provide for the first time an integrated regulatory tool, enabling the simultaneous consideration of the energy, environmental and economic parameters of buildings design. Its implementation, which is still facing delays, will prove the degree of its efficiency. This paper discusses the evolution of these developments within the framework of energy regulation over the last 30 years, with specific examples from Europe. The discussion focuses on the thermal insulation of the buildings envelope, the requirements for indoor air quality and the use of air conditioning, in order to narrow a subject that is too broad to be covered in its entirety. Developments from the first regulations in 1976 to Directive 2002/91 were neither straightforward nor solely driven by the rise of energy costs. They are based on the quest for an energy conscious, environmentally friendly and financially feasible building, which must also be friendly to its users.

Rating systems for counting buildings' environmental performance

The design, construction, use and demolition of buildings generate substantial social and economic benefits to society but may also have serious negative impacts especially for the environment. In response to the demand for evaluation and management of buildings’ environmental performance, several tools and methodologies have been developed and are being implemented in the construction sector aiming at sustainable performance. The research work is focusing on environmental management tools emphasising to rating systems’ analysis, comparison and implementation for buildings’ environmental performance. The LEED and BREEAM guides for existing buildings and new construction are compared, similarities and differences are analysed and a joint evaluation guide for existing buildings derived as a result of the rating systems’ analysis. Finally BREEAM and LEED were implemented to a new constructed multiuse office building in Greece in order to compare the results obtained.

Characteristics of wastes from electric and electronic equipment in Greece: results of a field survey:

The lifespan of electric and electronic equipment is becoming shorter and the amount of related waste is increasing. This study aimed to contribute to the knowledge about qualitative and quantitative characteristics of such wastes in Greece. Specifically, results are presented from a field survey, which took place in the city of Thessaloniki, Greece, during the year 2002. The survey was conducted with suitable questionnaires in department stores and in households of various municipalities. Household appliances were grouped as follows: (A) large (refrigerator, freezer, washing machine, clothes dryer, electric cooker, microwave oven, electric heater), (B) small (vacuum cleaner, electric iron, hair dryer), (C) information technology and telecommunication equipment(PC, laptop, printer, phone) and (D) consumer equipment(radio, TV, video, DVD, console). The analysis indicated that the lifespan of all new goods is gradually reducing (apart from refrigerators, for which the lifespan was surprisingly found to be increasing) and provided linearized functions for predicting the lifespan, according to the year of manufacture, for certain large appliances.

The impact of economic recession on domestic energy consumption

The ongoing economic recession that hit Greece in 2009 has considerably influenced the use of domestic heating sources, as households struggle to reduce energy consumption and the respective costs. With global energy demand and the heating oil prices being rather volatile, but not in extremis during the last five years, alternative heating systems with the respective resources are being considered by consumers, in order to cut down heating expenses. At the same time, these alternatives are not always the greener or the most sustainable ones. The current paper presents and analyses the impacts of the recession on the consumers’ behaviour regarding space heating. A field survey was carried out, by means of interviews with questionnaires, in Northern Greece, an area where there is an increased energy demand for heating and hence an intensive need for efficient solutions. The questionnaire was structured in an appropriate way in order to collect the available data, not only to identify the significant variables but also to capture any minor details that could be helpful in achieving our goal: gain reliable information about the energy consumption and the respective cost of heating at an annual base as well as their interconnection. The variables employed in the survey include among others: the building type, construction year, surface, main heating system, alternative heating systems (fireplace, AC unit, electric heater and stove), operating hours, saving measures, energy consumption and annual income. Any potential correlation between the aforementioned parameters will be explored while a mathematical description of their relation will be further attempted. The results of the survey carried out during 2011 and 2012 are presented and the most noteworthy conclusions are highlighted. The initial outcome proves that there is a certain trend of shrinkage of the households’ budget spent for domestic heating purposes as a consequence of the inhabitants’ income reduction and the dramatic tax increase on energy.

Sustainable building management: overview of certification schemes and standards

Building sustainable management is a complex problem which needs adequate and suitable assessment tools and methods, efficient enough, to address issues of incommensurability and complexity regarding environmental policies and legislation. Within the frame of this article, assessment methods have been described, are compared with each other and evaluated in the background of the standards provided by the International Organization for Standardization. The certification schemes examined include Building Research Establishment Environmental Assessment Method, Leadership in Energy and Environmental Design, Deutche Gesellschaft fur Nachhaltiges Bauen, Green Star, High Environmental Quality, Comprehensive Assessment System for Building Environmental Efficiency and GBTool assessment methods as well as the draft EU Ecolabel for office buildings. Emphasis have been placed on information referring to objectives, methodology, criteria involved in the evaluation procedure, environmental topics evaluated, life cycle analysis phases covered, costs and applications’ results within the tools’ structure for new building schemes. Finally, the impact of green certification schemes on the construction market, mainly as a tool of energy management, has also been examined in relation to the absence of mandatory international standardization in sustainable building management.

Residential photovoltaic systems in Greece and in other European countries: a comparison and an overview

One of the most promising renewable energy technologies (renewable energy sources, RESs) is photovoltaics (PVs). PVs are a truly elegant means of producing electricity on site, directly from the sun, without concern for energy supply or environmental harm. They represent a favorable case: easy and fast installation, low maintenance requirements and the ability to produce electricity on site within the urban built environment. In that sense, there is a growing consensus that PVs for individual buildings, known as building integrated or applied PVs (BIPVs or BAPVs, respectively), will be chief among the continuously widespread distributed PV applications. Still, they suffer from the disadvantage of their very high initial cost compared to other renewable and conventional energy technologies, although this has been steadily reduced during the last 5 years. It is therefore evident that without the support of suitable instruments, the expansion of solar electricity worldwide would not take place at a satisfactory pace. Various effective support mechanisms have been adopted, within which feed-in tariff (FiT) proved to be the most successful for PVs. That is the case also in Greece, where the PV market in the building sector grew rapidly after 2009, due to the great FiT incentives granted particularly for residential applications. In this paper an overview is provided, accompanied by a comparative feasibility study regarding residential PV systems’ prospects, based on the review of all kinds of incentive schemes in EU for small-scale BAPVs.