Temperatures measured at five locations in the building show the diurnal pattern typical of tropical climates, with strong diurnal fluctuations (10°C or more), but stable average conditions throughout the year (Figures 1B, 2B).
Minimum daily temperatures were typically observed at pre-dawn hours (5 am to 6 am), and varied from 18°C to 20°C during both rainy and dry seasons. Maximum daily temperatures were observed during the early afternoon (12 noon to 2 pm) and varied from 26°C to 28°C during both seasons. Average temperatures during working hours (8 am to 7 pm) were near 24°C to 25°C during both seasons.
Figure 1:
Diurnal patterns (in days) of illuminance, air temperature and relative humidity
inside the Holcim building during rainy and dry seasons
Illuminance (lum m-2) x 10-2
Temperature (°C)
Humidity (%)
Days
Compared with mean and maximum temperatures observed outdoors (22°C and 28.5°C, respectively), the building provided a comfortable climate, with indoor temperatures close to the average recorded outdoors, but with far lower maximum temperatures. The stairway between the ground floor and upper floor is an exceptional situation. This volume is wrapped in glass, which creates a greenhouse effect throughout the day. Temperatures here reached almost 32°C, uncomfortably hot. The temperature here is expected to drop substantially once the shading plants and trees grow.
Mean and maximum air temperatures predicted using the Comfort model were 24.9°C and 24.4°C during the dry season and 26.6°C and 25.9°C during the rainy season, respectively. In comparison with actual values measured in the building, the model underestimated maximum air temperature during the rainy season.
Figure 2:
Diurnal patterns (in hours) of illuminance, air temperature and relative humidity inside the Holcim building during rainy and dry seasons.
Illuminance (lum m-2) x 10-2
Temperature (°C)
Humidity (%)
Days
Relative humidity also showed typical tropical patterns (Figures 1C, 2C), characterized by strong diurnal and seasonal fluctuations. During the rainy season, average air humidity was close to 73% (table page 49). Humidity inside the building reached the highest levels at night (~ 90%) and progressively declined as air temperature increased during the daytime, reaching the lowest values around midday and early afternoon< (~ 50%).
In contrast, average air humidity during the dry season was only 53%. Indeed, maximum humidity during the dry season was typically below 80%, reaching lowest values close to 40% at midday and remaining low during the early afternoon. Humidity remained low (below 70%) during most of the working hours, causing a slightly uncomfortable climate for the occupants. In response, the misting system was installed in the courtyard to increase the humidity, cool the air, and improve indoor comfort.
Controlled amounts of air, heat, humidity, and light enter the offices in the south wing, creating a comfortable indoor environment that consumes very little energy.
During the second half of the rainy season (September to mid-November), winds blew predominantly from the southwest and showed a clear diurnal pattern. Wind speed was very low at night and increased to maximum values of 3 to 4 meters per second (mps) during the day. In contrast, air movement measured indoors reached much lower maximum values close to 0.6 mps, although gusts close to 3 mps were observed, which caused slight discomfort in some offices.
Figure 3:
Wind speed measured outside the building and air movement measured inside the building during the dry windy season.
Wind speed (mps)
Days
average
maximum
During the dry season, trade winds blowing from the northeast prevailed, with average values of 4 to 6 mps measured outdoors (Figure 3). These winds peaked at speeds greater than 10 mps. Inside the building, average air movement was usually lower than 0.5 mps, although gusts close to 2 mps were recorded.
Excessive air movement caused several problems. Papers were blown about and dust was spread, particularly during the early dry season. The excessive air movement made cooler weather chillier and made hot dry weather worse by contributing to dehydration and overheating. Air movement was an asset during hot and humid weather because natural ventilation speeds evaporation, thereby improving comfort. Ceiling fans were installed in some rooms (Figure 4).
Figure 4:
How fan operation during working hours affects air temperature inside the building during the dry season
Temperature (ºC)
Time of day
office with fan
office courtyard
office without fan