Energy consumption in both residential and public buildings has been established globally as been significantly high. The need to incorporate energy efficiency in building therefore becomes imperative in order to minimize the consumption level. This work therefore examines the effect of building orientation coupled with different building material composition on energy efficiency in building within major Nigeria climatic zones. The methodology adopted in this study entails carrying out a load survey and thereby calculating the cooling load required to condition the building space in two selected different orientations within the major Nigerian climatic zones. The standard cooling load equations were utilized in the evaluation of the various cooling loads. The selected locations considered within major Nigerian climatic zones are Ibadan in the South West, Jos in the middle belt and Maiduguri in the North East. The cooling load results obtained for the two different orientations are as follows; 151.45 kW and 163.17 kW for Ibadan, Maiduguri: 164 kW and 175.78 kW, and 131.77 kW, 143.4 kW for Jos. The first orientation being North/South longitudinal placement of the building while the second orientation is East/West longitudinal placement respectively. The study established that the second orientation generated more cooling load. It is therefore concluded that the first orientation which is the North/South longitudinal placement of the building is best recommended. It also established the dependence of cooling load on the climatic condition of the building’s location. Both building material compositions coupled with its orientation and climatic condition therefore play major significant role on the energy consumption in a building space.
Energy consumption in both residential and tertiary buildings in developed and developing countries is significantly high. Although there are already existing standard energy efficiency methods, efforts through research are still being made in trying to proffer solutions and mitigate energy consumption in the building sector to the barest minimum. Energy efficiency in buildings is multi-faceted. On one hand, the utilization of renewable and wastes leads to self-energy sufficient buildings. It could be said that they are the best option for the environment. However, self-energy sufficient buildings need usually high-tech systems, which can be unfeasible from the economic point of view. The continuous extraction of raw materials and production of building materials and systems can also cause environmental pollution. On the other hand, the utilization of modern energy-efficient buildings called intelligent buildings comes to fore. The systems in the building are controlled to assure the proper management of the energy demand, to conserve energy, to improve the comfort levels including indoor-air quality and to increase the building’s productivity through leveraging information. There has been an underlying global problem of insufficient energy production. The case of Nigeria is even worse, where the energy generated is far below the needed capacity, and yet much useful energy that is supposed to be conserved is being wasted or ill-utilized as a result of lack of government implemented policies and enlightenment programmes on the gains of adopting energy conservation measures on the environment and economic growth. It should be noted that, in the midst of the prevailing energy crisis in Nigeria, energy efficiency will play a pivotal role in ensuring access to energy. This study aims at investigating the load components of a building space and, subsequently analyzes the effects of building orientation and building material composition on the energy demand in buildings with in major Nigeria climatic zones.
Climatic design has been established as one of the best approaches to reduce the energy cost in buildings [
The author also studied the relationship between climate, building and occupants. He proposed several different strategies; the cooling and the day-lighting strategy. The cooling strategy include five concepts; solar control (protection of the building from direct solar radiation); ventilation (expelling and replacing unwanted hot air); internal gains minimization (reducing heat from occupants, equipment and artificial lighting); external gains avoidance (protection from unwanted heat by infiltration or conduction through the envelope in hot climates); natural cooling (improving natural ventilation by acting on the external air in hot climates). The day-lighting strategy include four concepts; penetration (collection of natural light inside the building); distribution (homogeneous spreading of light into the spaces or focusing); protect (reducing by external shading devices the sun’s rays penetration into the building); control (control light penetration by movable screens to avoid discomfort). His research aimed to provide a high level of building performance (BP), which could be defined as indoor environmental quality (IEQ), energy efficiency (EE) and cost efficiency (CE). Multi-criteria optimization of insulation options for warmth of buildings to increase energy efficiency investigated and established the enormous amount of energy consumed in existing buildings in Alipasino polje (Bosnia) [
Effect of building orientation on energy conservation was investigated by Odunfa K.M. et al. [
Sunday Oyedepo [
Nigeria is a country in the Western region of the African continent; Noted geographical features in include the Adamawa highlands, Mambilla Plateau, Jos Plateau, Obudu Plateau, the Niger River, River Benue and Niger Delta. Nigeria’s geographical coordinates are 10˚00'N, 8˚00'E. Although Nigeria is a tropical country, there exists a wide climatic variation in different parts. Near the coastline, temperatures are usually below 32˚C (90˚F), but the air is humid at night. Inland, there exists two seasons, a wet season from April to October with usually lower temperatures and a dry season from November to March, with a temperature range of 38˚C to 12˚C Nigeria is affected by four climate types; these climate types are distinguishable, as one transcends from the southern part of Nigeria to the northern part through the middle belt. Nigeria, like the rest of West Africa and other tropical lands, has only two seasons. These are the dry and the rainy season. The dry season being accompanied by a dust laden air-mass from the Sahara desert, locally known as harmattan and the rainy season is heavily influenced by an air-mass originating from the South Atlantic Ocean, locally known as the south west wind. Temperatures in Nigeria vary according to the seasons. Around March to April following the onset of the rainy season, temperatures can go as high as 44˚C (111.2˚F) in some parts of Nigeria. Semi temperate weather conditions prevail on the highlands in Central Nigeria at an altitude of 1217 meters (3993 ft) above sea level, namely the Jos Plateau. Average monthly temperatures in the Jos plateau ranges between 21˚C to 25˚C (70˚F - 77˚F), and from mid-November to late January, night time temperatures drop as low as 11˚C (52˚F). Jos receives about 1400 millimetres (55 inches) of rainfall annually. The city of Ibadan has a tropical wet and dry climate, with a lengthy wet season and relatively constant temperatures throughout the course of the year. Ibadan’s wet season runs from March through October, while the dry season runs from November to February. The mean total rainfall for Ibadan is 1420.06 mm, mean maximum temperature is 26.46˚C, minimum 21.42˚C and the relative humidity is 74.55%. The definition of climatic zones for architectural designs stems from the fact that climatic conditions and hence the requirements for thermal comfort are the basis for the selection of building form and building elements such as size of windows, insulation value of roofs and walls, the capacity of the air-conditioning equipment to be installed and the building orientation. It is therefore possible, to determine the approximate boundaries where a change in the climate and a change in thermal comfort requirements should be reflected in changed building form or changed building elements. These boundaries will effectively define the climatic zones for architectural design. The major climatic zones to be considered in this research study include, the tropical rainforest zone (parts of southern Nigeria), where the annual rainfall is between 60 to 80 inches (1524 to 2032 mm), the savannah zone (the middle belt), where the annual rainfall is between 20 to 60 inches (508 to 1524 mm) and the Arid zone (parts of northern Nigeria), where the annual rainfall is less than 20 inches (508 mm) per year. The major cities in these various Nigerian climatic zones to be studied are Ibadan, Maiduguri and Jos. Their locations lying in different climatic zones have been identified as shown in the map below in
In cooling load analysis in building, the followings are always taken into consideration; building characteristics, building location, orientation and external shading, weather data and selection of outdoor design conditions, selection of indoor design condition, indoor dry-bulb temperature, indoor wet-bulb temperature and ventilation rate, lighting, occupants, internal equipment, appliance and processes coupled with finally selection of the design level. For cooling load analysis in building, the following procedures as developed by the American Society of Heating, Refrigeration and Air-conditioning Engineers (ASHRAE) [
Building sunlight heat gain:
This includes the sunlight heat gains through the glass, the walls and the roof.
Building transmission heat gain:
This is the transmission heat gain through the glass and the appropriate building walls.
Infiltration heat gain:
This is the infiltration heat gain through the wall, door and window crack length.
Outside air by pass heat load:
This is the outside by-pass heat load through the ventilation and air conditioning
equipment bypass factor.
Internal heat load:
This load is generated by the occupants, machines, equipment, lighting fittings and any other heat generating devices inside the building.
Room latent heat:
These are the heat loads released by the occupants through infiltration and ventilation of the building.
The load is generated through the outside ventilation air and air-conditioning equipment bypass factor.
Cooling load classification with equations
Two ways of classifying the building cooling load are External and Internal loads classification. The classes are as follow with their equations:
External loads
1) Opaque elements located above ground (walls, roofs and doors) q s = U * A * C L T D .
2) Convective transfer through transparent assemblies (windows): q s = U * A * C L T D .
3) Radioactive transfer through transparent assemblies (window): q s = A * S C * S H E * C L F .
4) Ventilation and Infiltration air (sensible): q s = 1.08 * C F M * Δ T .
5) Ventilation heat load (latent): q L = C F M * Δ W * B F * 0.68 .
6) Infiltration heat load (latent): q L = C F M * Δ W * 0.68 .
Internal loads
1) Lighting systems: q s = i n p u t l a m p w a t t a g e * 3.41 * C L F .
2) People: a) sensible: q s = N * S H R
b) Latent: q L = N * L H R .
3) Equipment and appliances:
a) Sensible: q s = i n s t a l l e d w a t t a g e * C L F * 3.41
b) Latent: q L = i n s t a l l e d w a t t a g e * c l f * 3.41 .
4) Motor heat load: q s = M . H * 2546 * M E .
Grand total heat and refrigerator tonnage: By taking the sum of both external and internal heat loads, gives the grand total heat load of the space, Btu/h. The refrigeration load, tons, is gotten from (grand-total heat, Btu/h) (12,000 Btu/(h.Ton) (3577 W) of refrigeration).
Introduction
The design case study is the Faculty of Technology Lecture Theatre, University of Ibadan, Nigeria Figures 2-4 [
Design Assumptions
1) In this study the first orientation assumes the short and shaded side of the building is facing the East/West direction and the longer part facing the north/south direction (North/South longitudinal placement), while the second orientation assumes the short and shaded side of the building facing the north/south direction and the longer side facing the east/side direction (East/West longitudinal placement).
2) The roof is assumed to be a patch roof made of sheet metal, with a heat transfer coefficient, U of 0.27 Btu/h.ft2.0F, and insulated on the inside with suspended ceiling and it is directly facing the sun.
3) The glass window is assumed to be double hung and always closed with a crack-length of 726 ft and a heat transfer coefficient of 1.13 Btu/h.ft2.0F.
4) The wall type is under the Group D category. It is made of a 4-in hollow block, with a weight of 90 lb/ft2 and a heat transfer coefficient of 0.45 Btu/h.ft2.0F. It has a 5/8 plaster and is painted on both the inside and outside.
The results of the cooling load estimated when the building length is facing the east/west direction and when it is facing the north/south direction, and also the results when a different wall type is used, is as shown in a Tables 1-4. The amount of energy conserved in both cases in the two different orientations is
First Orientation | IBADAN | MAIDUGURI | JOS | |
---|---|---|---|---|
Sunlight Heat Gain | 117,247.2 | 132,608.24 | 99,427.68 | |
Transmission Heat Gain | 7322.4 | 10,576.8 | 813.6 | |
Infiltration Heat Gain | 5292.54 | 7644.78 | 588.06 | |
Outside Air Bypass Heat Load | 7020 | 10,140 | 780 | |
Heat Load from Internal Sources | 160,088.44 | 160,088.44 | 160,088.44 | |
Total Room Sensible Heat | 296,970.58 | 321,056.22 | 261,697.78 | |
Total Room Latent Heat | 248,410.56 | 259,218.58 | 235,801.32 | |
Total Outside Air Heat | 30,326.4 | 43,804.8 | 3369.6 | |
Grand Total Heat Load | 575,707.54 | 624,079.6 | 500,868.7 | |
Refrigeration Load | TONNS | 47.97 | 52.01 | 41.74 |
KILOWATT | 151.45 | 164.18 | 131.77 |
All parameters are in Btu/hr unless stated otherwise.
Second Orientation | IBADAN | MAIDUGURI | JOS | |
---|---|---|---|---|
Sunlight Heat Gain | 161,781.615 | 176,682.615 | 143,761.455 | |
Transmission Heat Gain | 7322.4 | 10,576.8 | 813.6 | |
Infiltration Heat Gain | 5292.54 | 7644.78 | 588.06 | |
Outside Air Bypass Heat Load | 7020 | 10,140 | 780 | |
Heat Load from Internal Sources | 160,088.44 | 160,088.44 | 160,088.44 | |
Total Room Sensible Heat | 341,504.995 | 365,132.635 | 306,031.555 | |
Total Room Latent Heat | 248,410.56 | 259,218.58 | 235,801.32 | |
Total Outside Air Heat | 30,326.4 | 43,804.18 | 3369.6 | |
Grand Total Heat Load | 620,241.955 | 668,155.395 | 545,202.475 | |
Refrigeration Load | TONNS | 51.68 | 55.67 | 45.43 |
KILOWATT | 163.17 | 175.78 | 143.4 |
All parameters are in Btu/hr unless stated otherwise.
First Orientation | IBADAN | MAIDUGURI | JOS | |
---|---|---|---|---|
Sunlight Heat Gain | 115,290.45 | 129,330.65 | 99,210.05 | |
Transmission Heat Gain | 7322.4 | 10,576.8 | 813.6 | |
Infiltration Heat Gain | 5292.54 | 7644.78 | 588.06 | |
Outside Air Bypass Heat Load | 7020 | 10,140 | 780 | |
Heat Load from Internal Sources | 160,088.44 | 160,088.44 | 160,088.44 | |
Total Room Sensible Heat | 295,013.83 | 317,780.67 | 261,480.15 | |
Total Room Latent Heat | 248,410.56 | 259,218.58 | 235801.32 | |
Total Outside Air Heat | 30,326.4 | 43,804.8 | 3369.6 | |
Grand Total Heat Load | 573,750.79 | 620,804.05 | 500,651.07 | |
Refrigeration Load | TONNS | 47.81 | 51.73 | 41.72 |
KILOWATT | 150.94 | 163.32 | 131.71 |
All parameters are in Btu/hr unless stated otherwise.
Second Orientation | IBADAN | MAIDUGURI | JOS | |
---|---|---|---|---|
Sunlight Heat Gain | 156,724.415 | 170,764.615 | 140,425.855 | |
Transmission Heat Gain | 7322.4 | 10,576.8 | 813.6 | |
Infiltration Heat Gain | 5292.54 | 7644.78 | 588.06 | |
Outside Air Bypass Heat Load | 7020 | 10,140 | 780 | |
Heat Load from Internal Sources | 160,088.44 | 160,088.44 | 160,088.44 | |
Total Room Sensible Heat | 336,447.795 | 359,217.635 | 302,695.955 | |
Total Room Latent Heat | 248,410.56 | 259,218.58 | 235,801.32 | |
Total Outside Air Heat | 30,326.4 | 43,804.18 | 3369.6 | |
Grand Total Heat Load | 615,184.755 | 662,237.395 | 541,866.875 | |
Refrigeration Load | TONNS | 51.26 | 55.18 | 45.16 |
KILOWATT | 161.84 | 174.22 | 142.56 |
All parameters are in Btu/hr unless stated otherwise.
also shown.
From
LOCATION | ORIENTATION | REFRIGERATION LOAD | |
---|---|---|---|
TONNAGE(TONNS) | KILOWATT(KW) | ||
IBADAN | FIRST | 47.97 | 151.45 |
SECOND | 51.68 | 163.17 | |
MAIDUGURI | FIRST | 52 | 164 |
SECOND | 55.67 | 175.78 | |
JOS | FIRST | 41.73 | 131.77 |
SECOND | 45.43 | 143.4 |
ORIENTATION | |||||||
---|---|---|---|---|---|---|---|
LOCATION | FIRST(HEAT LOAD) | SECOND(HEAT LOAD) | |||||
BTU/HR | TONN-AGE | ELECTRI-CAL ENERGY(KW) | BTU/HR | TONN-AGE | ELECTRI-CALENERGY(KW) | ELECTRICALENERGY CONSERVED (KW) | |
IBADAN | 575,707.54 | 47.97 | 151.45 | 620,241.955 | 51.68 | 163.17 | 11.72 |
MAI-DUGURI | 624,079.6 | 52.01 | 164.18 | 668,155.395 | 55.67 | 175.78 | 11.6 |
JOS | 500,868.7 | 41.74 | 131.77 | 545,202.475 | 45.43 | 141.4 | 9.63 |
ORIENTATION | |||||||
---|---|---|---|---|---|---|---|
LOCATION | FIRST(HEAT LOAD) | SECOND(HEAT LOAD) | ELECTRICALENERGY CONSERVED (KW) | ||||
BTU/HR | TONN-AGE | ELECTRI-CAL ENERGY(KW) | BTU/HR | TONN-AGE | ELECTRI-CALENERGY(KW) | ||
IBADAN | 575,707.54 | 47.97 | 151.45 | 620,241.955 | 51.68 | 163.17 | 11.72 |
MAI-DUGURI | 624,079.6 | 52.01 | 164.18 | 668,155.395 | 55.67 | 175.78 | 11.6 |
JOS | 500,868.7 | 41.74 | 131.77 | 545,202.475 | 45.43 | 141.4 | 9.63 |
ORIENTATION | |||||||
---|---|---|---|---|---|---|---|
LOCA-TION | FIRST(HEAT LOAD) | SECOND(HEAT LOAD) | |||||
BTU/HR | TONN-AGE | ELECTRI-CAL ENERGY(KW) | BTU/HR | TONN-AGE | ELECTRI-CALENERGY(kw) | ELECTRI-CALENERGY CONSER-VED(KW) | |
IBA-DAN | 573,75079 | 47.81 | 150.94 | 615,184.755 | 51.26 | 161.84 | 10.9 |
MAI-DUG-URI | 620,808.05 | 51.73 | 163.32 | 662,237.395 | 55.18 | 174.22 | 10.9 |
JOS | 500,051.07 | 41.72 | 131.71 | 541,866.875 | 45.16 | 142.56 | 10.85 |
cooling load. The higher values gotten when the building was reoriented is as a result of a larger and longer area of the building construction now facing the direction of the sun. The disparity in the values gotten from both orientations is understandable, since of all the factors that can affect the cooling load of a building space, the orientation of the building contributes the greatest amount This is the major reason why a proper building orientation should be adopted, with respect to the direction of the sun, in other for energy to be duly conserved. The electrical energy conserved as a result of the building orientation is demonstrated in
From the line graph shown in Chart 1 and Chart 2, it can be seen that the
LOCATION | ORIENTATION | REFRIGERATION LOAD (KW) (REGULAR BLOCK) | REFRIGERATION LOAD (KW) (BRICK MASONRY) | ELECTRI-CAL ENERGY CONSER-VED(KW) |
---|---|---|---|---|
IBADAN | FIRST | 151.45 | 150 | 1.45 |
SECOND | 163.17 | 161.84 | 1.33 | |
MAIDUGURI | FIRST | 164 | 163.22 | 0.78 |
SECOND | 175.78 | 174.22 | 1.56 | |
JOS | FIRST | 131.77 | 131.71 | 0.06 |
SECOND | 143.4 | 142.55 | 0.85 |
Chart 1. Cooling load in the two different orientations in Nigeria major climatic zones.
Chart 2. Cooling load estimates in the two different orientations in major Nigerian climatic zones.
cooling load decreases from the arid zone (Maiduguri) to the tropical rainforest zone (Ibadan) and the savannah zone (Jos). The cooling load in Jos is lower than the others because of the higher elevation, the higher air moisture content level or specific humidity and the cold and temperate weather. The cooling load in Maiduguri is larger because of the dry, hot and more tropical climate (equatorial) prevalent in most northern states in Nigeria, as compared to the south.
This work has fully and successfully examined the effects of building orientation on energy efficiency in a building. Buildings should be constructed and equipment selection and installation made according to the climate of the place. The results obtained from this research work will be able to provide information, enlightenment and advice to both private individuals, government institutions, building engineers and consultants coupled with the facility managers on the importance of adopting energy efficiency and how electrical energy could be saved up when energy efficiency policies are adopted. Presently, the current status of Nigerian building performance generally does not conform to the outcome result of my study, and in fact it is just the opposite when talking about the rural settlement areas.
The authors declare no conflicts of interest regarding the publication of this paper.
Odunfa, K.M., Nnakwe, C.J. and Odunfa, V.O. (2018) Building Energy Efficiency in Nigeria Major Climatic Zones. Journal of Building Construction and Planning Research, 6, 251-266. https://doi.org/10.4236/jbcpr.2018.64017