**5. Conclusions**

The aim of this paper was first, to diagnose construction defects that may affect the thermal integrity of the building's envelope in both existing and under-construction housing projects in Al Ain in the United Arab Emirates. Second, we intended to identify the prevailing and subsequent impacts of the identified building defects through a qualitative review analysis.

The thermal behavior and construction quality of residential building envelopes were assessed through an infrared thermography audit performed on several existing and under-construction residential units under the extreme hot climate of Al Ain (UAE). The analysis highlighted three major areas of defects: lack or discontinuity in building envelope insulation, thermal bridging, and discrepancies due to non-compliant design changes. Unexpectedly, in existing buildings the results exhibited more thermal anomalies in newer units than in older ones, indicating that building thermal performance was more a function of workmanship and construction quality than mere building age. The most frequent recurring defect in units under construction was thermal bridging between the non-insulated reinforced concrete structural frames and insulated concrete block, which occurred in all cases examined except in the housing using precast panels, a defect that will compromise the targeted thermal performance of the exterior walls. Another diagnosed defect was the oversized service outlets and mortar joints, which were recurring defects that, in turn, affected the thermal integrity of walls. Finally, non-compliant design changes in the construction phase with improper or non-compliant implementation resulted in clear thermal bridging. In the under-construction housing units, the analysis indicated poor workmanship, absence of coordination during design changes, and incorrect construction details as the root causes of the defects. Hence, these may well be related to the general lack of understanding of thermal insulation, scarcity of skilled labor, and insufficient or inadequate site coordination, supervision, and construction quality control during construction.

Next, a qualitative review analysis identified the impacts of these defects. The existing literature provided evidence on the occurrence frequency of the identified defects in different contexts. The lack of insulation in the building envelope was found to be a common issue in all pre-code era housing, an expected outcome in context due to the late implementation of strict building energy efficiency regulations in the UAE that mandated, from 2010, thermal insulation. This issue dramatically increased heat transfer and energy consumption while it also affected energy cost and user comfort. Besides the overall envelope insulation, thermal bridging through walls, roof, and wall openings as well as at joints and connections was a recurrent issue with numerous measurable negative impacts. Thermal bridges were analyzed per type of defect, highlighting in all cases the negative impact on energy loss, increased energy cost, and substantial impact on the health and comfort of users. Research indicated that the presence of lower thermal performance and surface condensation led to hygiene problems such as mold growth and the staining of surfaces, which, in turn, affected the users' comfort levels. On the other hand, poor workmanship managemen<sup>t</sup> and design discrepancies were found to be critical sources of defects. Predicting and evaluating the impact of the construction workmanship is difficult; therefore, allowances should be considered in the overall predicted building energy performance balance.

These results and their multiple impacts on energy, cost, health, and comfort call for engaging an energy professional to ensure compliance with the targets during all the construction stages as well as an effective reconsideration of the quality control process during construction to ensure the designed building meets its intended standards, expected thermal performance, and users' well-being.

**Author Contributions:** Conceptualization, K.A.T.A.; methodology, K.A.T.A. and R.H.; formal analysis, K.A.T.A., R.H., R.A., M.S., B.A.; investigation, R.H., R.A., M.S., B.A., resources, All; writing— original draft preparation, All; writing—review and editing, K.A.T.A.; visualization, R.H., R.A.; supervision, project administration; funding acquisition, K.A.T.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** The authors gratefully acknowledge financial support from the United Arab Emirates University through the Emirates Centre for Energy and Environment Research funded research project N. 31R102 and the SURE Plus undergraduate research funded projects Grant N. G00002503 and G00002866.

**Conflicts of Interest:** The authors declare no conflict of interest.
