Vital Signs
Project: A Tale of Two Houses
 Figure 8a: Indoor/Outdoor Temperature - Cairo Villa (25K JPEG)
In order to manage the analysis of the different data collected from multiple sources,
two analytical categories were developed. These analytical categories are based on the
three hypothesis speculated earlier. These are:
Hypothesis 1 & 2: Hassan Fathy's house (Mit Rehan) would have better thermal
performance than Cairo villa, and thus reduce energy levels due to natural cooling.
Although the data collected from the "HOBO" dataloggers (Figure 8) shows that
the indoor temperature in Mit Rehan is 2-3 deg C lower than that in the Cairo villa, the
difference is not significant to confirm the previously stated hypothesis (Figure 9,
below). The difference between the sky and indoor temperatures for both buildings is
almost equal. This, however, can pose a different hypothesis related to the interaction
between thermal mass and thermal resistance in reducing cooling loads and thus energy
conservation. While other factors remain constant, the two main differences in the two
houses vital statistics is their thermal storage mass and the rate of heat transfer
between the building and the ambient enclosure (Ubldg.) (See Table 2 in the previous
section).
 Figure 8b: Indoor/Outdoor Temperature - Mit Rehan (25K JPEG)
 Figure 9: Comparison of Interior House Temperatures (21K JPEG)
Hassan Fathy's house with a larger thermal mass (three times larger thermal mass) has
the same thermal behavior as the more insulated Cairo villa (50% better Ubldg.). Thus the
reduction in energy levels is not due to the reduction of cooling loads as speculated in
the second hypothesis, yet might be due to the reduction in the overall life cost energy
consumption of the building.
This result might suggest the success of Hassan Fathy's building strategies in
conserving energy when considering the overall life cost analysis of the building. Using
simple construction techniques and relying mainly on recycled wood scraps (for the wood
shutters at Mashrabiyas, Figure 3) and low-machinery construction, the building provided
the same indoor conditions as the more technological sophisticated Cairo Villa. This
finding might suggest new implications towards the life cost energy analysis of buildings
as related to the overall sustainability of the global environment.
 Figure 10a: Relative Humidity - Mit Rehan (32K JPEG)
 Figure 10b: Temperature at Sky and Shade - Mit Rehan (33K JPEG)
 Figure 11a: Relative Humidity - Cairo
Villa (22K JPEG)
 Figure 11b: Temperature at Sky and Shade (29K JPEG)
Occupant Perceptions
Interviews with Mit Rehan's occupants revealed that perceived thermal comfort inside
spaces covered with domes and vaults was much higher than inside spaces covered with flat
roofs. This might be related to the better performance of curved surfaces due to their
lower degree of sky exposure and self shade. Occupants' of Cairo Villa also reported their
perception of higher thermal comfort in places that carry certain meaning to them and that
were associated with warm feelings in their life history (e.g. family room next to a fire
place, even when the fire is not on, play room even when it has been transformed to an
office space after the children grew-up, etc.). This finding suggests that the user's
perception of thermal comfort is not merely due to the "PPD" and
"MPV's" as suggested by Fanger's (1982) comfort equations. Future research has
to acknowledge other psychological personal factors beside metabolic rate and clothing
insulation that might have an effect on the users indoor comfort. In addition, future
research should acknowledge association to the building's form and the symbolic effects of
certain architectural elements such as domes and vaults on the users perceived comfort.
Hypothesis 3: Hassan Fathy's architecture satisfies the users needs and
"wants" and maintains a traditional heritage of the region.
This conceptual hypothesis is subject to future investigations. The results of the
conducted interviews and field research suggests that the users association and
"wants" as related to the building form and architectural elements are related
to the context where the building is located. Interviews with the users of Mit Rehan as
well as lay people surrounding the setting indicate their satisfaction with the building
style as it matches the surrounding environment. This is due to the relationship between
the form and colors of Mit Rehan to the country side of its surrounding environment.
Interviews with the owners of the Cairo Villa as well as other occupants of similar
contemporary houses revealed that Hassan Fathy's neo-traditional architecture might be
less favored in the city's urban in-fills as it would not match the surrounding urban
fabric and the "image" of the city's modern planning. Most respondents associate
this building style with countryside and suburban housing. As one interviewee mentioned:
"Mit Rehan's architecture is fitting its location and context here, in the
countryside or suburban development. I don't think its architectural style would be
favored in the city quarters or city neighborhoods. People are not used to houses with
domes and vaults in the city, they might even have a different interpretation for it and
associate it to a mosque or a religious building or mausoleum."
(Interview # 7, August 7, 1996) |
