Constantinos A. Balaras

Potential for energy conservation in apartment buildings

Abstract The potential for energy conservation in apartment buildings is investigated following the epiqr methodology and software. Several scenarios are evaluated for various apartment buildings located in three climatic zones of Hellas. The proposed retrofit actions concentrate on space heating and cooling, domestic hot water production and lighting. Energy savings for the corresponding actions in each building are accounted for in order to identify the most effective scenarios, suitable for different building constructions, installations and system characteristics.

Comparison of methodologies for tmy generation using 20 years data for Athens, Greece

Abstract The need of accurate Test Reference Years (TRYs) for simulations has been well recognised over the years. Various methods for deriving TRYs have been developed, but their final results can be significantly different. In this paper, the major methodologies reported in literature were applied to 20-year hourly measurements of weather data from Athens, covering the period 1977 to 1996. Seventeen TRYs were produced in total. The basis to select the “best” performing TRY includes meteorological criteria (inherent in the selection process used by each method) and comparisons of results from various simulations for typical energy systems (i.e. a solar water heater, a building, a large scale solar heating system with interseasonal storage and a photovoltaic system). Based on the results of each simulation exercise, a scoring system was developed and applied. The best performing TRY was found to be the one produced by a modified Festa-Ratto method.

Energy conservation strategies for sports centers: Part B. Swimming pools

This paper summarizes the results from a number of energy audits and the analysis performed in order to improve indoor conditions and optimize energy use, in Hellenic indoor swimming pools, performed for the European Commission, in the framework of the SAVE program. The aim of this work was to investigate the technical, functional and administrative obstacles for energy conservation in sports centers (including sports halls) and to propose practical and cost-effective solutions for improving their energy efficiency, indoor thermal and visual comfort throughout the year. The work concentrated on retrofitting of existing buildings, although the proposed design and management principles could also be followed in new projects in the area of sports and recreation facilities.

CO2 emission reduction policies in the greek residential sector: a methodological framework for their economic evaluation

This paper outlines a methodological framework for the economic evaluation of CO2 emissions abatement policies and measures in the residential sector, taking into consideration both economic and social costs/benefits. The approach includes two stages: first, the measures under consideration are evaluated on the basis of a cost effectiveness analysis, which takes into account only the related net financial costs, thus highlighting win–win actions (i.e. measures presenting an economic benefit for end users without the provision of any economic subsidies or other similar policies); and second, the measures are re-evaluated using an integrated cost benefit analysis (where both the private and external costs/benefits are taken into account). The economic performance of the measures examined incorporates the effects of a variety of parameters, such as the region’s climate, size and age of buildings, etc., which significantly affect the resulting ranking. The implementation of this framework in the Greek residential sector identified and prioritized a significant emissions reduction potential, which could be achieved with win–win measures and/or interventions that present a net social benefit. Measures with negative economic cost but positive net social benefit for the majority of the buildings examined include: (i) regular inspection of central heating boilers, (ii) use of thermostats in central heating boilers, (iii) sealing of openings, (iv) installation of solar collectors for hot water etc. The monetization of environmental benefits is shown to provide a powerful tool for highlighting priority actions in the context of a climate change mitigation policy.

Active solar space heating of residential buildings in northern Hellas—a case study

Abstract The final energy consumption in Hellenic residential and tertiary sector buildings represents almost one-third of the total energy budget. From this, space and water heating represents 70% of the total. Space heating and electricity generation in Hellas are based on fossil fuels, with a serious environmental impact. Despite the popularity of simple solar domestic hot water systems, active solar space heating remains, for various reasons, marginal. The aim of this paper is to demonstrate the potential of combined active space and domestic hot water solar systems, both technically and economically. An assessment of the reduction of the environmental impact is also included. The results confirm that modern solar technology constitutes a viable option for energy retrofit in the building sector in Hellas.

EPIQR surveys of apartment buildings in Europe

A total of 38 apartment building surveys following the EPIQR methodology have been performed in seven European countries. The audits included the energy systems, indoor environmental conditions and building envelope. The collected data provide a novel overview on the condition, construction characteristics, installations, energy systems and consumption of existing residential buildings throughout Europe. A comparative analysis of the data will reveal the common characteristics and differences in terms of energy behavior, indoor environmental quality and building structure for the existing building stock in Europe and examine potential implications of the forthcoming European action on labeling of buildings.

Energy conservation strategies for sports centers : Part A. Sports halls

This paper summarizes the results from a number of energy audits and the analysis performed in order to improve indoor conditions and optimize energy use, in Hellenic sports halls, performed for the European Commission, in the framework of the SAVE program. The aim of this work was to investigate the technical, functional and administrative obstacles for energy conservation in sports centers (including swimming pools) and to propose practical and cost-effective solutions for improving their energy efficiency, indoor thermal and visual comfort throughout the year. The work concentrated on retrofitting of existing buildings, although the proposed design and management principles could also be followed in new projects in the area of sports and recreation facilities.

Energy policy and an action plan for renewable energy sources (RES) for the Hellenic islands of the North Aegean region

The resource base for RES is vast, but only a small fraction is being exploited with available technology. The full potential of RES for the European Union (EU) is estimated at 408 Mtoe by 2020. Here, we review data on energy supplies and demand with emphasis on RES and also assess the potential for energy conservation by using RES in remote regions. Our case study deals with the Hellenic islands of the North Aegean region. These islands have a high RES potential because of their dependence on external energy sources, absence of control over fossil-fuel costs and periodic power shortages, especially during summers when energy demands peak as a result of tourism.

Development of improved solar radiation models for predicting beam transmittance

Abstract A pair of enhanced models are presented herein which, while relying only on global irradiation measurements, result in increased predictive power in estimating the hourly beam irradiation. The first model correlates the beam transmittance with clearness index and air mass. The second correlates the beam transmittance with the clearness index and with a new variable based on the temporal variation of the global radiation. The new variable helps describe the sky condition without the need of any further meteorological information. The models were developed using a new surface fitting technique applied to data which were collected at the Solar Total Energy Project in Shenandoah, Georgia (33.4°N, 84.7°W) over a five-year period.

Evaluation of different radiation and albedo models for the prediction of solar radiation incident on tilted surfaces, for four European locations

The diffuse radiation incident on an inclined surface is composed of both the sky diffuse radiation and the ground-reflected radiation. Depending on the model used to calculate the sky diffuse radiation and the estimated albedo value, it is possible to introduce a significant error in the prediction of the total radiation incident on a tilted surface. Twelve sky diffuse submodels associated with four different albedo submodels are used to estimate the total radiation on the tilted surface from data on the horizontal plane. The predicted total solar radiation values are compared with measured data on a south facing vertical surface, from four representative south and north European locations. Root mean square error, mean bias error, and a t-test are used to determine the intrinsic performance of each combination of diffuse tilt and albedo submodel. Accordingly, the various model combinations do not exhibit a statistically significant difference between measured and calculated values.