Abstract
Energy saving and Indoor Air Quality (IAQ) in buildings are strongly affected by air leakages. Several studies reveal that the energy loss owing to leaky windows can account for up to 40% of the total building energy demand. Furthermore, at the design stage, the possible infiltration of outdoor air through windows is not taken into account when determining the nominal outdoor airflow rate of the ventilation system. This practice may result in an oversizing of the ventilation system and consequent energy waste. Thus, the air-tightness class of a wall assembly should be assessed for each window component considering the type of material, the presence of the seal, the type of closure, the sealing and the maintenance condition. In this paper, the authors present the experimental results of air-tightness measurements carried out using the fan pressurization method in three residential buildings located in the Mediterranean region before and after a window retrofit. Two different window retrofits were investigated: the application of rubber seals on window frames and the substitution of existing windows with new certified high performance windows. The effectiveness of such retrofits was estimated also in terms of energy saving. Test results demonstrated a high variability of the building air tightness after window retrofits, despite the fact that air tight–certified windows were used.
Highlights
IntroductionOperating on opaque and transparent walls is an effective strategy to reduce heat losses through the building envelope
The retrofit of existing residential stock provides significant opportunities and challenges in terms of new systems and components and in terms of the related energy saving [1,2].Operating on opaque and transparent walls is an effective strategy to reduce heat losses through the building envelope
Energy saving and Indoor Air Quality (IAQ) in buildings are strongly affected by air leakages
Summary
Operating on opaque and transparent walls is an effective strategy to reduce heat losses through the building envelope. The retrofit of opaque elements is often difficult, especially when buildings exhibit historical constraints (e.g., in Mediterranean countries) or aesthetic peculiarities that avoid invasive solutions such as external insulation. On the other hand, operating on windows is undoubtedly easier and this can be applied to historical buildings [3] by reproducing the original window frame with high performance materials. In recent decades there has been an increased focus on the reduction of the thermal transmittance of building components [4,5] and related measurement techniques applicable in the field [6]. The requirements for ensuring buildings’ air-tightness are too often disregarded [7]
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