4.1. LEED-CI v4 Categories
Table 2 presents analyses of the eight LEED categories and total LEED values.
IP showed a low achievement level (0.0) and an infinite (Inf) IQR/M value in Spain, a moderate achievement level (1.0) and a high IQR/M value (2.0) in Türkiye, and a high achievement level (2.0) and a zero IQR/M value in Israel. Israel outperformed Spain and Türkiye in the IP category (
p = 0.005 and 0.023, respectively). In [
19], IP showed a high achievement level (2.0) and a high IQR/M value (0.5) in China, and it showed a moderate achievement level (1.0) and high IQR/M value (2.0) in the USA. Thus, Israel and China showed the best results, Türkiye and the United States obtained intermediate results, and Spain achieved the worst results.
IP contains one credit, Integrative Process (IPc1), with two points. This credit requires an early analysis of energy and water systems to provide a strong foundation for energy- and water-saving opportunities in the EA and WE categories [
3]. IP achievement is associated with EA achievement.
EA showed moderate achievement levels (19.0 and 20.0) and high IQR/M values (0.47 and 0.34) in Spain and Türkiye, respectively, and it showed a high achievement level (28.0) and a low IQR/M value (0.19) in Israel. Israel outperformed Spain and Türkiye in the EA category (
p = 0.086 and 0.010, respectively). In [
19], EA showed a low/moderate achievement level (16.0) and a low IQR/M value (0.25) in China, and it showed a moderate/high achievement level (22.5) and a high IQR/M value (0.58) in the USA. Thus, Israel showed the best results; Spain, Türkiye, and the USA achieved intermediate results; and China had the worst results.
MRs showed low achievement levels (5.0, 3.0, and 1.0) and high IQR/M values (0.40, 0.42, and 3.75) in Spain, Türkiye, and Israel, respectively. Israel showed an extremely high IQR/M value of 3.75. An extremely high value may indicate that there are at least two different subgroups within this group. Spain outperformed Türkiye and Israel in MRs (
p = 0.010 and 0.0003, respectively). In [
19], MRs showed a low achievement level (3.0) and a high IQR/M value (0.67) in China, and MRs also showed a low/moderate achievement level (5.0) and a high IQR/M value (0.50) in the USA. Thus, Spain and the USA showed the best results, China and Türkiye achieved intermediate results, and Israel showed the worst results.
The MRs category contains several points that require a life cycle assessment (LCA) to demonstrate the sustainability of a product [
3]. LCA includes hundreds of processes (resources and power) and productions (emissions and unwanted or unusable materials) that are consumed/emitted throughout a product’s whole life cycle (production, service, and demolition stages). It is a time-consuming and labor-intensive process [
33]. Thus, an analysis of MRs credits could clarify Spain’s better performance compared with Türkiye and Israel.
LT displayed high achievement levels (17, 16, and 15.0) and low IQR/M values (0.18. 0.08, and 0.05) in Spain, Türkiye, and Israel, respectively. However, Spain and Türkiye outperformed Israel in the LT category (
p = 0.042 and 0.002, respectively). The analyzed LEED-certified projects were located in the high-density urban cities of Madrid, Spain (3.2 million people in an area of 604 km
2, giving urban density of 5300/km
2) [
34]; Istanbul, Türkiye (15.4 million people in an area of 5313 km
2, giving urban density of 2910/km
2) [
35]; and Tel Aviv, Israel (1.4 million people in an area of 176 km
2, giving urban density of 8000/km
2) [
36]. It is possible that, in the aforementioned densely populated cities, more public services and transport options required for the LT category can be easily accessed [
37].
In [
19], LT showed a high achievement level (17.0) and a low IQR/M value (0.06) in China, while LT showed a high achievement level (17.0) and a high IQR/M value (0.35) in the USA. China outperformed the USA in the LT category (
p < 0.001). Thus, Spain and China showed the best results, Türkiye and the USA achieved intermediate results, and Israel showed the worst results.
WE showed a low/moderate achievement level (8.0) and a high IQR/M value (0.75) in Spain and Israel, and a moderate achievement level (19.0) and a high IQR/M value (0.40) in Türkiye. There were no differences in WE between countries (0.198 ≤
p ≤ 0.906). The WE category has one credit, WEc1. WEc1 is associated with reduced indoor water use, and it is likely impacted by water scarcity in Mediterranean climates with high temperatures and low rainfall levels. In Spain, there is a tight balance between existing water resources and current needs, including for drinking water [
38]. Türkiye’s water shortage situation has been aggravated by strong population growth [
37]. Israel, despite undertaking desalination of the Mediterranean Sea to obtain drinking water, is also experiencing rapid population growth, which is exacerbating the problem of water shortages [
39]. Therefore, the issue of water conservation is of high priority in these three countries.
In [
19], WE showed a high achievement level (12.0) and a low IQR/M value (0.17) in China, while WE showed a moderate achievement level (6.0) and a high IQR/M value (0.33) in the USA. Thus, China showed the best results; Spain, Türkiye, and Israel showed intermediate results; and the USA obtained the worst results.
EQ showed low achievement levels (6.5, 5.0, and 6.0) and high IQR/M values (0.46, 0.60, and 0.50) in Spain, Türkiye, and Israel, respectively. There were no differences in the pairwise comparisons between Spain, Türkiye, and Israel in the EQ category (0.421 ≤
p ≤ 0.820). The EQ category contains occupant-related credits such as adequate lighting (EQc6), appropriate thermal comfort (EQc5), air quality (EQc1 and EQc3-4), and acoustic performance (EQc9) [
3].
In [
19], EQ showed a low/moderate achievement level (7.0) and a low IQR/M value (0.29) in China, while EQ showed a low achievement level (6.5) and a high IQR/M value (0.62) in the USA. Thus, China showed the best results; Spain, Israel, and the USA showed intermediate results; and Türkiye achieved the worst results.
IO showed a high achievement level (5.0) and a low IQR/M value (0.20) in Spain, and it showed moderate achievement levels (3.0 and 3.0) and high IQR/M values (0.75 and 0.67) in Türkiye and Israel, respectively. Spain outperformed Türkiye and Israel in the IO category (p = 0.036 and 0.016, respectively). It can be assumed that in Spain innovative building technologies are more actively used in LEED-certified projects than in Türkiye and Israel.
In [
19], IO showed a high achievement level (5.0) and low IQR/M value (0.20) in China and a high achievement level (5.0) and high IQR/M value (0.40) in the USA. Thus, Spain and China showed the best results, the USA showed intermediate results, and Türkiye and Israel obtained the worst results.
RP showed high achievement levels (3.5 and 4.0) and low IQR/M values (0.29 and 0.25) in both Spain and Israel, respectively, and it showed a moderate achievement level (2.0) and a high IQR/M value (0.63) in Türkiye. Spain and Israel outperformed Türkiye in the RP category (p = 0.013 and 0.006, respectively). It can also be assumed that in Spain and Israel, RP credits are more actively used in LEED-certified projects than in Türkiye.
In [
19], RP showed moderate/high levels (3.0 and 3.0) and high IQR/M values (0.33 and 0.33) in both China and the USA. Thus, Spain and Israel showed the best results, China and the USA achieved intermediate results, and Türkiye showed the worst results.
The summarized results obtained in this study for Spain, Türkiye, and Israel, as well as the results obtained previously [
19] for China and the USA, are presented in
Table 3.
Table 3 showed three-valued logic results for these five countries in terms of LEED-CI v4 gold-certified projects at the categorical level.
Spain achieved the best results four times (MRs, LT, IO, and RP), intermediate results three times (EA, WE, and EQ), and the worst result once (IP). Türkiye achieved intermediate results (IP, EA, MRs, LT, and WE) five times, and the worst results (EQ, IO, and RP) three times. Israel achieved the best results (IP, EA, and RP) three times, intermediate results (WE and EQ) twice, and the worst results (MRs, LT, and IO) three times. China achieved the best results (IP, LT, WE, EQ, and IO) five times, intermediate results (MRs and RP) twice, and the worst result (EA) once. The USA achieved the best result (MRs) once, intermediate results (IP, EA, LT, EQ, IO, and RP) six times, and the worst result (WE) once. Thus, a comparative analysis of the descriptive statistics between countries was found to be a relevant method for assessing LEED certification strategies.