ROW HOUSING DEVELOPMENT ENUGU (A STUDY
ON PASSIVE CLIMATE CONTROL IN A TROPICAL
Comfort within buildings is primarily controlled by four major factors: air temperature, mean radiant temperature, humidity, and airflow (air movement). Each can have a dominating effect. Their effects are not necessarily additive and practically never linear. There are other factors which affect comfort including clothing, activity level, and climatization. With these factors posing a threat to human psychology and well-being it is without doubt that comfort remains a key factor in residential developments especially in developing nations like Nigeria where power supply is erratic. In view of that, the study attempts to review various concepts in attaining thermal comfort. The research also relates to Vernacular Architecture techniques to achieve thermal comfort through efficient means, and
its various elements and usage for modern architecture. It also presents and analyzes passive design climate control systems as a concept in achieving comfort and an energy efficient design. It goes further to investigate climatic conditions in the tropics emphasizing more on the climate of Enugu.
Methods and elements of passive design climate control techniques were discussed and researched by concerned individuals were also analyzed especially those most important to row housing developments in the tropics. The paper discusses row housing type, its origin and preference in the temperate regions (Western countries); the favouritism emerged primarily because of its ability of the cluster house type to retain heat gained during the day needed obviously to heat up their buildings. Notwithstanding, the reverse is the case in the tropics as attempts are made to keep heat away from interior spaces in building. Against these many odds the paper recommends this housing type in Enugu because of its sustainable nature as translated in its maximization of land. Finally the study analyzes the challenge of adapting a concept constructively in line with the temperate zone in a tropical context (Enugu) through various passive design climate control techniques and transmitting the ideas into an actual design configuration that will tackle the obvious problems of ventilation and solar radiation in row housing design.
No building can turn out to be a Work of Architecture without first meeting the requirements of realism. This includes Utility in the sense that a building must serve the various purposes it is intended for. Economical in the light that within a reasonable cost the building must be constructed and maintained in addition to sustaining its value with the passage of time. Environmentally friendly; with consideration given to the use of materials that are renewable, using minimum amounts of total energy from extraction, processing, shipping, and installation of the materials and in the operation and maintenance of the Building.
Reliable, that is the Building must be well built to resist the various deteriorating forces to which it could be subjected. And finally a building must be comfortable; with consideration given to proper lighting, climate control, sanitation, acoustics, circulation, and healthy environments. The paper focuses on the economical realism and comfort pragmatism of a building and its environment. It proposes passive climate control systems as a vital tool in achieving comfort and sustainability in buildings in the tropical environment especially in Nigeria where power supply is erratic (it is estimated that the population is effectively short of power supply over 60 percent of the time Okoye 2007).
Row housing type was singled out and analysed also in this paper. Its peculiar problems as regards to indoor thermal comfort and how to achieve a controlled climate within the housing type using passive climate control systems. Key terms- passive climate control, row house, thermal comfort, climate responsive design,
sustainability, and tropical environment.
DEFINITION OF TERMS
Passive design climate control: This is improving comfort conditions without the use of any electromechanical systems. Climate responsive design: These are designs that ensure a comfortable environment, less energy usage and reduced green house gas emission. Tropical environment: Can be referred to the environment or areas that lie within the tropics. The tropics lie along the equator, between the Tropic of Cancer in the northern hemisphere at approximately 23° 26′ 16″ (or 23.4378°) N and the Tropic of Capricorn in the southern hemisphere at 23° 26′ 16″ (or 23.4378°) S and can be distinguished by hot humid conditions. Mean annual temperatures reach a maximum of 30ºC during the day and a minimum of 24ºC at night. Humidity levels vary between 60% – 100% and a tropical climate is accompanied with high levels of rainfall, during ‘rainy periods’ where annual mean rainfall can exceed1000mm. Thermal comfort: An internationally-accepted definition of thermal comfort, used by ASHRAE, is ‘that condition of mind which expresses satisfaction with the thermal environment’ (ISO 7330). Perceptions of this environment are affected by air temperature, radiant temperature, relative humidity, air velocity, activity and clothing. More general
definitions of comfort include a sense of relaxation and freedom from worry or pain.
Sustainability: The Brundtland Commission, formally the World Commission on Environment and Development (WCED) defines sustainability as meeting the needs of the present without compromising the ability of future generations to meet their own needs. is simply able to be maintained or exploiting natural resources without destroying the ecological balance of an area. United States environmental protection agency (EPA), defines sustainability as the ability of an ecosystem to maintain a defined/desired state of ecological integrity over time. Row house: Also called “town houses”; also called “terraced home”: 3 or more houses in a row sharing a “party” wall with its adjacent neighbour. They are typically multiple stories.
1.1 BACKGROUND OF STUDY
Enugu is located in a tropical rain forest zone with a derived savannah. The city has a tropical savanna climate. Enugu’s climate is humid and this humidity is at its highest between March and November. Other weather conditions affecting the city include Harmattan, a dusty trade wind from the north east lasting a few weeks of December and January. Like the rest of Nigeria, Enugu is hot all year round. Fig 1.1 map showing the tropical climate regions (source: www.meteoblue.com/en_GB/content/438) Enugu is known for its good soil and climatic conditions all year round, sitting at about 223 metres (732 ft) above sea level, and the soil is well drained during its rainy seasons. The mean temperature in Enugu State in the hottest month of February is about 87.16 °F (30.64 °C), the lowest temperatures occur in the month of November reaching 60.54 °F (15.86 °C), while the mean daily temperature is 26.7 °C (80.1 °F). The lowest rainfall of
about 0.16 cubic centimetres (0.0098 cu in) is normal in February, the highest is about 35.7 cubic centimetres (2.18 cu in) in July, while the average annual rainfall in Enugu is around 2.0 cubic centimetres (0.122047 cu in), which arrives intermittently and becomes very heavy during the rainy season. Enugu is regarded as a tropical state and it lies on latitudes 6°24’and 6°30′ and longitudes 7°26′ and 7°30′, it is bounded in the west by a north-south trending escarpment and in the east
by Cross River Plains. The population of Enugu state is put at 3,257,298 according to the population census of 2006(www.total-facts-about-nigeria.com)
Housing in Enugu over time has always been the priority of the government, but the recent government has taken the course more seriously than any other government much as to incorporating it in their four point agenda. The government has promised to
Fully monetize government houses to public servants on owner-occupation basis.
Develop new middle and low income houses (a target of minimum of 500 units a year) in partnership with the Federal Mortgage Bank under the National Housing
Fund Scheme for sale to public servants and other contributors to the NHF.
Create new estates and satellite towns with full site and services for sale to members of the public.
According to Enugu State Housing Development Corporation (ESHDC) report the Enugu state government has 12 estates that are either completed or ongoing.
Riverside Housing Estate Abakpa Nike
Trans Ekulu Housing Estate Enugu
Real Estate Uwani
Republic Layout Estate
Harmony Estate, Umuchigbo iji Nike
Ebeano Housing Estate Indepence Avenue Enugu.
Golf Course Estate Enugu.
Q-Services Estate Enugu (Governmnet House)
Coal City Gardens Estate G.R.A. Enugu.
Ekulu East Housing Estate
The Enugu public private partnership housing scheme (EPPHS) has built large number of residential buildings (239 housing unit) for Enugu citizens and about 64%of the population lives in it (www.enuguppphousing.com) Most Enugu buildings old, new, and ongoing rely on a combination of cross ventilation and
mechanical ventilation by fans to achieve thermal comfort. However, the climate condition of Nigeria might have negative impact on the comfort of the occupants.
Over the years, the living standard in Enugu has improved. To improve the thermal environment, more and more occupants install air conditioners. The most obvious side effect is the dramatic rise in energy consumption in the domestic sector. In Nigeria, the energy consumption has more than doubled since 1980, from just 0.42 quadrillion BTU (quads) in 1980 to about 1.13 quads in 2004 according to (www.allbuisness.com) Passive climate control is the concept completely in line with the notion of sustainable building. It is an alternative to a mechanical air-conditioning system and as such is an essential part of sustainable building.
Passive climate control implies that the structure is built and arranged in such a way that the thermal and hygroscopic properties of the building and its
contents create a good stable indoor climate (Christoffersen, 1995). Only buildings that are climate responsive adhere completely to the concept of passive climate control. According to Gut & Ackerknecht, (1993): The main points to take into consideration when designing a climate responsive building are
minimize heat gain during daytime and maximize heat loss at night in hot seasons, and reverse cold seasons,
minimize internal heat gain in the hot seasons,
select the site according to microclimatic criteria,
optimize the building structure (especially regarding thermal storage and time lag),
control solar radiation,
Regulate air circulation.
The practice of sustainable/ environmentally friendly design tends to have captured the imagination of most people living in developed nations. Most sustainable design methods and bioclimatic data have been developed, are mature and fairly easily accessible within these countries in general. However this does not mean that sustainable or green design is not applicable within developing nations or in the tropics. As with most developing nations, as new technologies are introduced and people get progressively wealthier, the drive for mechanical means to achieve human comfort increases. Air conditioning is now a widely used and accepted way of life, still buildings built in Nigeria are not really designed to use air conditioning effectively. Nigerians now install casement or sliding windows which further reduces ventilation in replacement of the old style jalousie or louvered windows. Yet the buildings themselves are not insulated, windows and
doors do not have proper seals to prevent the heat from the exterior penetrating the structure. You end up with a building or home that is bleeding money through wasted energy from an air conditioner struggling to keep a building cool against all odds.
What happens in these buildings the moment you turn off the air conditioner? They get stifling hot within minutes. So you have buildings not designed to work with the climate and have technology that is inefficient. Since buildings accounts for 30% of a country’s energy according to the United states department of energy, one can see why for a developing nation, sustainability should be a priority.
ROW HOUSING DEVELOPMENT ENUGU (A STUDY
ON PASSIVE CLIMATE CONTROL IN A TROPICAL
1.2 STATEMENT OF ARCHITECTURAL PROBLEM
Ventilation and lighting are major problems in row housing structures especially in the tropics. The research will be faced with analyzing the intricacies in achieving an effective climate control mechanism devoid of mechanical strategies. The architectural design will be faced with the challenge of transforming the research data
and models into a workable design configuration suitable for the tropical environment. The study should transmute into a design that ought to encourage further development of the housing type, and finally create a model for housing that will generally be accepted and appreciated by the people of Enugu.