![Source:Liebardet al,2005.
Solar radiation is only useful in practice when at right- angles to glazed surfaces, by
which it is partly transmitted into the inner space and provides a direct heat gain. Solar
radiation often produces heat when not needed. It is therefore, useful to be able to store
heat until it is needed. This storage takes place within all types of material according to
their capacity to accumulate heat. Distributing heat around a building whilst regulating it
means conveying it to the different living spaces where it is desired. This distribution can
be carried out naturally when the heat accumulated in materials during periods of the
sunisreleasedback intothe ambient airby radiationandconvection.
Studyarea
Figure 3:TheHeating Strategy
Enugu is a city in south-eastern Nigeria, located at 6.26° north and 7.29° east. The climatic
data of Enugu as shown in gure 4 can be classied as the tropic rain forest. Enugu covers
a total area of 215 sqmi (556 km2) with a population density of 3,400/sq mi (1,300/km2).
Located in the basin of the Cross River and the Benue Trough, it has the best-developed
coal in Nigeria. The city is on an altitude of 304.7 m above sea level, its climate is naturally
humid, and this humidity is high between March and November [11]. Its average
maximum temperature stands at 34.9°C, with average lows of about 22.3°C and its
annualmeantemperature isabout 26.7°C[11].
Figure 4:ClimaticdataofEnuguCity
Source:NIMETyear endedin2017.
IJSRETH | 44](https://image.slidesharecdn.com/article4-220410170755/85/ARTICLE4-pdf-5-320.jpg)
ARTICLE4.pdf
- 1. 1,2,3&4 Department ofArchitecture, Keywords: Bioclimatic design strategies, Energy Efciency, Residential Buildings, Warm HumidClimate Corresponding Author: Nnaemeka-Okeke R.C. University of Nigeria, Enugu Campus, Enugu 1 2 3 4 Nnaemeka-Okeke R.C, Okeke F.O, Okwuosa C.C.& Sam-Amobi C. Bioclimatic Design Strategies for Residential Buildings in Warm Humid Tropical Climate of Enugu, Nigeria A Bioclimatic designed building responds to the climatic conditions within its environment as they are modied with appropriate design strategies to create a conducive environment that provides thermal and visual comforts to its users at the lowest energy consumption. The study is carried out to review bioclimatic design strategies for residential buildings in a warm humid climate of Enugu using the Psychrometric chart adapted from Giovani to analyze the climate of the study area and identify the bioclimatic design strategy that will aid energy efciency. The research methodology adopted is a review of existing literature for warm humid climate d And nally, a proposal that can be applied to residential building design in Enugu was developed. This study helps us conclude that some bioclimatic design strategies can be used in countries with similar climates and therefore, advocates for more incorporationofbioclimaticdesignstrategies forenergy-efcient buildings. A b s t r a c t International Journal of Strategic Research in Education, Technology and Humanities |IJSRETH p-ISSN: 2465-731X | e-ISSN: 2467-818X Volume 6 Number 2 December, 2019 http://internationalpolicybrief.org/journals/international-scientic-research-consortium-journals/intl-jrnl-of-strategic-research-in-edu-tech-humanities-vol6-no2-december-2019 IJSRETH | 40
- 2. iii. Torelate bioclimaticprinciplestobuilding designinawarm-humidzone. Bioclimatic architecture is dened as a design that has a connection with nature. It considers the climate and environmental conditions to favour the thermal comfort of users (Liebard, &Traité 2005). There is integration between the design and natural elements; the sun, wind, rain and vegetation, which optimizes resources. A bioclimatic design considers climate and environmental conditions to help achieve optimal thermal comfort indoors (Chayaamor-Heil, &Hannachi-Belkadi, 2017)was coined by the Olgyay's in the early 1960s. The bioclimatic design approach could be simply described as architecture design methods that take advantage of the climate through the right application of design elements and building technology for energy savings, as well as to ensure comfortable conditions in buildings (Olgyay, 1973). It refers to the study of climate when applied to Architecture, to improve the conditions of thermal comfort of the occupants using appropriate design strategies, which differs from place to place based on the prevailing climate of that place. Researchers have identied that buildings are responsible for approximately 40% of the total world annual energy consumption of which most of the energy consumed is for the provision of lighting, heating, cooling, and air conditioning (HVAC). The heating and cooling of a space to maintain thermal comfort are an energy-intensive process that represents up to 60–70% of the total energy consumption in non-industrial buildings ( In Nigeria, energy consumed by Omer, 2008). residential buildings accounts for more than 50% of the total energy consumed in the country ( Hence, the concept of green development Energy Commission of Nigeria, 2014). through bioclimaticbuilding designs. Problem Denition i. Toreviewthe conceptandprinciplesofbioclimaticdesigns. ii. Toanalyze variousBioclimaticPrinciplesandindividualapplication AimandObjectivesof theStudy the research aims to is to study bioclimatic principles and their application in the design of residential buildings in a warm humid climate to achieve adequate thermal comfort of occupants,with specicobjectivesasfollows: Nowadays, Architects design buildings using the principles of sustainable design (Akadiri, (2016). But there is a challenge in integrating climate control and building functionality to achieve thermal comfort in the environment while reducing the effect of solar radiation, wind, and rain. Many architects do not integrate the bioclimatic approach into their designs because of their lack of condence (Wei Zhu &Zhuo Wang, 2016).This is because of their notion that the integration of bioclimatic design requires the knowledge of “green technology”. Other architects complete the design process before passing the whole scheme to the engineers. Therefore, a study of bioclimatic architecture will expose themtothe bioclimaticdesignstrategies(Maeiel&Lamberts,2007). iv. Toproposea frameworkthat willbe adoptedforresidentialbuildingsinEnugu. IJSRETH | 41
- 3. BioclimaticDesignStrategies The natural lighting strategy aims to improve how natural light is captured and allowed to penetrate a building and enhance how it is then diffused and focused (Chayaamor- Heil&Hannachi-Belkadi,2017) The Control of light to avoid visual discomfort therefore must be considered because excessive natural light penetration can cause visual discomfort and glare which can be controlled by constructing xed architectural features such as overhangs, roof lights or light-shelves, roof eaves, etc. in conjunction with adjustable screens (awnings, shutters, louvre-shutters or blinds) as illustrated in gure 1. The intelligent use of natural light enables the reduction of electricity consumption for lighting. Lateral lighting provides a directed light that highlights outlines but is limited in-depth unlike top lighting which is more uniform but possible only on the top oor of buildings. The principle behind the bioclimatic design is the understanding of the climatic factors of a site by analyzing the inuence of microclimate; including solar radiation, sunshine, temperature, humidity, rainfall, wind velocity and direction (Hyde 2000). Bioclimatic structures are constructed in such a way that, during winter months, exposure to cold temperatures is minimized and solar gains are maximized; during the summer, bioclimatic structures are shaded from the sun and various cooling techniques are employed, often with the aid of renewable energy sources (Manzano-Agugliaroet al, 2015). NaturalLightingStrategy Figure 1:Strategies toControlthe Entry ofNatural Light Source:Liebardet al,2005. The amount of light captured in a room depends on the position, orientation, angle, size, nature and the type of glazing surface, its roughness and thickness. The construction of the window surrounds may also create a barrier to direct sunlight into the building while reective ground surfaces like paving or swimming pool may contribute to capturing more light.The way light penetrates a building creates very diverse lighting effects and depends on the type of sky, atmospheric disturbances, season, time of day, and how open the siteis. IJSRETH | 42
- 4. Cooling Strategy The cooling strategy is a response to the need for thermal comfort. This can be achieved by shading from solar radiation and heat gain, minimizing internal heat sources, dissipating excess heat and cooling down naturally. The minimizing of internal heat sources is aimed at avoidingexcessiveheat inbuildingsduetothe occupantsandtheir equipment. The heating strategy is a response to winter comfort. Heat is captured from solar radiation and stored in the mass of the building. It is then retained and distributed around the building. The solar radiation received by a building depends on the climate with its daily and seasonal variations, the orientation of the building, the nature of its surfaces and the materialsused,onthe topography ofthe site,onthe shade,etc. Figure 2:Strategies forCoolingInBuildings Shading is required to shield the building openings from direct sunlight to limit direct heat by using screens, window hood or ns also shown in gure 2. Also, walls can be prevented from heating up by insulation. Cooling in buildings can easily be achieved by natural means of ensuring good ventilation (especially at night, to eliminate heat stored up during the day) or to increase the speed of air circulation (the Venturi effect, wind towers, etc.). Other means of cooling is by using water features like fountains and swimmingpool,trees,landscapeandundergroundducting. Source:Liebardet al,2005. TheHeatingStrategy IJSRETH | 43
- 5. Source:Liebardet al,2005. Solar radiation is only useful in practice when at right- angles to glazed surfaces, by which it is partly transmitted into the inner space and provides a direct heat gain. Solar radiation often produces heat when not needed. It is therefore, useful to be able to store heat until it is needed. This storage takes place within all types of material according to their capacity to accumulate heat. Distributing heat around a building whilst regulating it means conveying it to the different living spaces where it is desired. This distribution can be carried out naturally when the heat accumulated in materials during periods of the sunisreleasedback intothe ambient airby radiationandconvection. Studyarea Figure 3:TheHeating Strategy Enugu is a city in south-eastern Nigeria, located at 6.26° north and 7.29° east. The climatic data of Enugu as shown in gure 4 can be classied as the tropic rain forest. Enugu covers a total area of 215 sqmi (556 km2) with a population density of 3,400/sq mi (1,300/km2). Located in the basin of the Cross River and the Benue Trough, it has the best-developed coal in Nigeria. The city is on an altitude of 304.7 m above sea level, its climate is naturally humid, and this humidity is high between March and November [11]. Its average maximum temperature stands at 34.9°C, with average lows of about 22.3°C and its annualmeantemperature isabout 26.7°C[11]. Figure 4:ClimaticdataofEnuguCity Source:NIMETyear endedin2017. IJSRETH | 44
- 6. The rainy and dry seasons, particularly with West Africa, are the only weather cycles in Enugu. The mean wind speed is 5.5 m/s between March and September with an average of 7.1 m/s in August. Typical wind path comes relatively from the west for an average of 10 months (termed the monsoon season), ranging from January to November, with a peak percentage of about 75% occurring in July (Akubue, 2019). Also, in the harmattan season, the wind now changes direction to the north from November to January, with 41% occurringin the peak monthofJanuary (Akubue, 2019). Methodology The methodology of this study is a review of various literatureon bioclimatic strategy in the warm humid climate and relating it to the climate of Enugu. The Psychometric chart, which was adopted from (Givoni, 1992) was used to analyze the climatic condition of the study area. The bioclimatic design strategy that will aid thermal comfort and improve energy efciencywillalsobe identied. The Givoni chart shown in gure 5 is a bioclimatic diagram that has been divided into different zones for which it is necessary to use strategies to achieve human comfort within a building. The x-axis represents the dry bulb temperature and the y-axis shows the fresh air humidity; psychometric curves in the graph represent the relative humidity. Here, 14 zonesaredenedbasedondenitionsofbulb temperature andfreshairhumidity. Figure 5:PsychometricChart Source:Givoni(1992) From there, zones 1 and 2 are the ideal comfort zones. Thus, we can dene climatic conditions and the associated architectural strategies to shift the environmental conditions of the home into the comfort zone. Whenever possible, passive strategies will IJSRETH | 45
- 7. a) Minimizingheat gainsin building be proposed, as these consume zero energy. When this is not possible, these strategies will be applied to help reduce the use of energy-consuming devices to the lowest possible levels. To study the possible bioclimatic architectural strategies, we must rst evaluate the conditions in which the home is located. The environmental conditions will place us within a zone in the Givoni diagram. If we are in the comfort zone, the architecture will not have to perform any thermal corrections but if we are outside of the comfort zone, architecturalstrategies canbe implementedtoreachthe comfortzone. Discussion In a hot and dry climate, compact buildings with small windows and a high thermal mass are preferred; in a war humid climate, buildings with more openings and permeable are considered.Thetwomaingoalsforinformingthe designdecisionare: 1. Understandingofclimateandclimatezones Through wide literature review, appropriate strategies evolved includes Giovani's Concept, Enugu can be said to be in zone 8 where temperature values are from 20 or higher. In this case, bioclimatic architecture strategies attempt to avoid heat gains through solar radiation and avoid temperature increases to remain in the comfort zone. Protection is focused on all building openings but can also be generally applied to the building envelope. Solar protection can be implemented naturally such as the use of trees or through architectural elements such as pergolas with vegetation, porches, awnings, andblinds. Findings 3. Identifythe sourcesofheat BioclimaticDesignStrategiesinaWarm HumidArea b) Enhancingheat losswherepossible 4. Optimization ofmicro-climaticconditions Achieving thermal comfort in a warm humid area, heat absorption and heat storage are avoided, while the use of double skin structures, low thermal mass and high reective outer surfaces is ideal. Indoor temperature is maintained by proper design for ventilation and utilization of air movement at an increased velocity, which takes the advantage of reducingheat andthe humiditylevel. The bioclimatic approach tends to apply the passive design which saves energy using daylighting and wind passively, without conversion of solar and wind to electrical energy. The passive design in warm humid areas like Enugu, nd out ways to prevent building heating caused by solar radiation, without sacricing the needs of natural lighting. Also, the use of wind as natural ventilation is explored to obtain optimal thermal comfort. This submission agrees with the ndings of (Sharma, 2016), who assert that the passive system in bioclimatic design can be attained through the following basic strategies: 2. Identicationofthe comfortzone IJSRETH | 46
- 8. 5. Dening the characteristicsrequiredforthe congurationofbuilding and Furthermore, Yeang (1996). mentioned that an important component in bioclimatic design is passive cooling for indoor air condition. This technique provides cooling by using air to carry heat out of the building by convection cooling and, from the human body by physiological cooling. The effectiveness is determined by outdoor conditions, microclimate and characteristics of the building i.e. building orientation, number and sizes of openings. To achieve thermal comfort through natural ventilation, windows will be openable and will be placed adjacent to each other for cross ventilation. Landscape elements like tress can be used to direct the wind. In the case where natural cross ventilation is not possible to achieve, stack effect can be used to get a chimney effect. The framework for bioclimatic design strategies to achieve the optimal thermal comfort in a warmhumidenvironmentissummarizedasfollows: BuildingDesign Orientation: Correctbuilding placementandorientation Provide overhangs or outward shading for north and south-facing windows 6. the building envelope Daylighting zones Designwith Courtyards Windowswith Visible Light Transmittance60%forgooddaylighting ConclusionandRecommendation Bioclimatic design by extension is a Green design building approach. There is no better time other than now for Nigeria to pursue green designs and technologies to combat present and future challenges (Okekeet al2018).The premise of the bioclimatic design strategy is that buildings utilize natural heating, cooling, and daylighting in accordance to local climatic conditions. Therefore, we can derive the appropriate bioclimatic design strategies that will be suitable for a warm humid climate by analyzing the design with regards to natural ventilation, daylighting, and passive heating and cooling. By adopting these strategies of bioclimatic building designs, the energy required for cooling and lighting a building will be reduced especially in the residential building type where Useopenandpermeablegeometry allowingairow Useforthat provideBufferzonesandthermalzoning Materialwith Lowthermalmass Buildingform: Useroofswith High SolarReectiveIndex Windowsshouldopentowardsthe prevailing wind Materials: Goodlandscapeplanning IJSRETH | 47
- 9. Manzano-Agugliaro, F., Montoya, F. G., Sabio-Ortega, A., Garcia-Cruz, A. (2015). Review of bioclimatic architecture strategies for achieving thermal comfort”, Renew. Sustain.Energy Rev.,49:736–755. Maeiel, A,, Ford, B., Lamberts, R.(2007). Main inuences on the design philosophy and knowledge basis to bioclimatic integration into architectural design: The exampleof best practices.Buildingandenvironment,42(10),3762-3773. Akadiri, P. O. (2016). Evaluating the performance of bioclimatic design building in Nigeria, Civil and Environmental Research. ISSN 2224-5790 (Paper) ISSN 2225-0514 (Online) 8,(5) 2016. Akubue, A. J., (2019). Effects of street geometry on airow regimes for natural ventilation in Three different street congurations in Enugu City, Different Strategies of Housing Design,AyşemBerrinÇakmaklı, IntechOpen, DOI:10.5772/intechopen.84786. Energy Commission of Nigeria, (2014). Overview of the building energy efciency guideline (BEEG)forNigeria. Hyde, R. (2000). Climate responsive design: a study of buildings in moderate and hot humidClimates,NewYork:EandFN Spon. References Olgyay, V. (1973). Design with climate: Bioclimatic approach to architectural regionalism: Princeton UniversityPress. Givoni, B. (1992). Comfort, climate analysis and building design guidelines, Energy and Buildings18 (1):11–23. Chayaamor-Heil, N. Hannachi-Belkadi, N. (2017). Towards a platform of investigative tools for Biomimicry as a new approach for energy-efcient building design. MAP- Maacc,CNRS-MCCUMR3495, ENSAPARIS-La-Villette,Paris(75),France; Liebard, A. De-Herde, A. Traité (2005). D'architecture et D'urbanismeBioclimatiques: Concervoir, Édier et AménagerAvec le Développement Durable, Observ'ER: Paris, France,2005. Okeke F. O etal (2018). Green Architecture the Nigerian Perspective, International Journal of Agriculture, Environment and Bioresearch 3, (06); 2018 ISSN: 2456-8643, www.ijaeb.orgPage 341. people spend most of their time. Residential buildings also will not only benet from reduced energy usage as a result of these bioclimatic measures, but will provide a more comfortable indoor climate for occupants, reduce the negative environmental impact, andbe moreeconomicallysustainable. IJSRETH | 48
- 10. Wei Zhu Zhuo Wang (2016). Bioclimatic Design Approach Integration into Architectural Design: A Library Case Study. International Conference on Passive and Low Energy Architecture. Cities, Buildings, People: Towards Regenerative Environments Omer, A. M. (2008). Energy, environment and sustainable development, Renewable and SustainableEnergy Reviews, Elsevier, 12(9),pages 2265-2300. Sharma, R (2016). Sustainable buildings in hot and dry climate of India. Journal of Engineering Research andApplications6(1):134-144. Yeang, K.(1996).Theskyscraper Bioclimaticallyconsidered,Chichester:AcademyEditions. IJSRETH | 49