Hrvoje Krstić

EVALUATING THE AIRTIGHTNESS OF RESIDENTIAL BUILDINGS BY USING PREDICTIVE MODELS

A building’s energy consumption can be greatly reduced by improving its airtightness. Thus, when designing new and retrofitting existing buildings,

INFLUENCE OF WINDOW TYPE ON THE AIRTIGHTNESS OF RESIDENTIAL UNITS

Airtightness plays a significant role in the energy efficiency of buildings. In this paper, we investigated how varying the type of window affects the airtightness values of residential units. We studied three sets of residential units, each comprising two residential units with the same geometry and year of construction, varying only the installed window type and window-frame material. A brief explanation is included of the blower-door method, used in field-testing the airtightness of residential units. Replacing the old windows in the residential units with newer windows significantly improved the airtightness. To generalize these results, further research is needed with larger samples.

Maintenance and operation costs model for university buildings

Costs of maintenance and operation are important part of the Life cycle costs. This paper describes development and validation of a new model for predicting average annual costs of maintenance and operations for the University buildings in Osijek with similar building characteristics. The model is developed based on historical cost data records obtained from 13 University buildings in Osijek for time period of 12 years starting from 1998. The model was tested at two new sets of data, in buildings outside of Osijek. The proposed operating and maintenance costs model requires reduced amount of data for predicting annual maintenance and operations costs of University buildings of similar building characteristics and highlights statistically significant data required for costs prediction. The model contains only few elements but yet can predict operating and maintenance costs. The proposed model enables maintenance and operations cost estimates already at the initial design phase.

Review of Methods for Buildings Energy Performance Modelling

Research presented in this paper gives a brief review of methods used for buildings energy performance modelling. This paper gives also a comprehensive review of the advantages and disadvantages of available methods as well as the input parameters used for modelling buildings energy performance. European Directive EPBD obliges the implementation of energy certification procedure which gives an insight on buildings energy performance via exiting energy certificate databases. Some of the methods for buildings energy performance modelling mentioned in this paper are developed by employing data sets of buildings which have already undergone an energy certification procedure. Such database is used in this paper where the majority of buildings in the database have already gone under some form of partial retrofitting – replacement of windows or installation of thermal insulation but still have poor energy performance. The case study presented in this paper utilizes energy certificates database obtained from residential units in Croatia (over 400 buildings) in order to determine the dependence between buildings energy performance and variables from database by using statistical dependencies tests. Building energy performance in database is presented with building energy efficiency rate (from A+ to G) which is based on specific annual energy needs for heating for referential climatic data [kWh/(m2a)]. Independent variables in database are surfaces and volume of the conditioned part of the building, building shape factor, energy used for heating, CO2 emission, building age and year of reconstruction. Research results presented in this paper give an insight in possibilities of methods used for buildings energy performance modelling. Further on it gives an analysis of dependencies between buildings energy performance as a dependent variable and independent variables from the database. Presented results could be used for development of new building energy performance predictive model.

ANALIZA STVARNIH I PLANIRANIH TROŠKOVA ODRŽAVANJA I UPORABE GRAĐEVINA

Analiza održavanja i uporabe građevina opisuje se kao skup trajnih aktivnosti koje sadrže tehnicka i pridružena im administrativna djelovanja, k