Experimental design applied to modeling of air-tightness of a building Abstract: The paper presents experimental designs that can be used in modeling of the air-tightness of buildings as second-order functions using response surface method and corresponding experiment designs. The factors supposed to be significant for a model of building air-tightness-and thus those used in experiment designs-are the heat transfer coefficient for external walls, the heat transfer coefficient of the windows, and the position of the housing units with respect to the building envelope. We compared three-level full factorial and fractional factorial designs, as well as central composite designs and the Box-Behnken design.Keywords: air-tightness, design of experiment, factorial designs, central composite designs, Box-Behnken design VRSTE PLANOVA EKSPERIMENTA ZA MODELIRANJE ZRAKOPROPUSNOSTI ZGRADA Sažetak: U radu su prikazane vrste planova eksperimenta koje se mogu koristiti za modeliranje zrakopropusnosti zgrada, a definirane su preko funkcije drugog reda pomoću metode odzivne površine i odgovarajućeg plana eksperimenta. Faktori koji bi trebali biti važni za model zrakopropusnosti zgrade te stoga upotrijebljeni u planu eksperimenta, su koeficijent prolaska topline za vanjske zidove, koeficijent prolaska topline za prozore i položaj stambenih jedinica u odnosu na ovojnicu zgrade. Uspoređeni su potpuni faktorski plan i djelomični faktorski plan na tri razine, te centralno kompozitni i Box-Behnkenov plan eksperimenta.Ključne riječi: zrakopropusnost, plan eksperimenta, faktorski plan, centralno kompozitni plan, Box-Behnkenov plan