Low-cost retrofit packages for residential buildings in hot-humid Lagos, Nigeria

PurposeThe dearth of green standards (GS) in sub-Saharan Africa is alarming and the green cost premiums (GCP) in seeking certification in emerging markets are scanty. This paper studied the Building Energy-Efficiency Code of Nigeria (BEEC) and estimated the potential GCPs associated with the various energy-efficiency ratings.Design/methodology/approachThe study retrofitted 150 conventional residential bungalow and maisonette buildings using BEEC's energy-efficiency interventions and performed analytical estimating of the retrofitted designs. The mean cost premium associated with each energy-efficiency intervention is presented as well as their financial benefits and payback periods. The benefits are achievable financial-savings due to a reduction in energy consumption and savings in electricity payment estimated from the average energy demands of each building. An independent t-test was further conducted to determine the cost differential between energy-efficient design (ED) and conventional design over a five-year period.FindingsThe potential GCPs and their payback periods are actually less than feared. The study showed that less than 5% and 21% extra funding would be required to achieve 1 to 4-Star and 5-Star energy-efficiency ratings involving passive design interventions and photovoltaic systems. Passive and active design interventions produced a financial savings of $8.08/m2 in electricity payment and $2.84/m2 per annum in energy consumption reduction. The financial-savings ($10.92/m2) was objective to pay-off the GCPs in less than four years. The independent t-test analysis showed the cost of ED is more economical after four years into the project lifecycle.Originality/valueThe research provides cost benchmarks for navigating cost planning and budgetary decisions during ED implementation and births a departure point for advancing energy-efficient construction in developing markets from the rational economic decision perspective.

Section: Literature Reviewmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Green cost premium for attaining energy-efficiency rating in Nigeria's hot-humid residential buildings

Ekung

Odesola

Adewuyi

2021

“…The computer modeling techniques have been widely promoted in the current literature as a useful, accurate, efficient, and reliable tool for building optimization (Olaniyan, 2012). They save time and money compared with a range of available quantitative research methods (Onyenokporo and Ochedi, 2019). In this study, a simulation study using the EnergyPlus simulation tool in DesignBuilder was adopted to test a selected building prototype that represents the dominant residential building for an average low-and middle-income earners.…”

Section: Introductionmentioning

confidence: 99%

Optimization of building envelopes using indigenous materials to achieve thermal comfort and affordable housing in Abuja, Nigeria

Taki

2021

PurposeThis paper aims to demonstrate the optimization of an existing residential building in a tropical climate using indigenous materials as an alternative to conventional building envelopes to achieve thermal comfort and affordable housing.Design/methodology/approachThis study mainly adopted a quantitative research methodology through a comprehensive simulation study on a selected prototype building. The energy plus simulation tool in DesignBuilder was used to predict the average monthly and annual thermal comfort of a typical residential building in the study area. Also, a cost analysis of the final optimization interventions was conducted to estimate the construction cost savings.FindingsThe comparative analysis of simulation results for the base-case and optimized models indicates potential advantages in replacing conventional building envelope materials with indigenous materials. The base-case simulation results showed that the annual operative temperature is more than the adaptive thermal comfort set points in tropical climates, by 8.26%. This often leads to interventions using mechanical cooling systems, thus triggering overconsumption of energy and increase in CO2 emissions. The building envelope materials for floor, walls and roof were replaced with low U-values indigenous materials until considerable results in terms of thermal comfort and overall building construction cost were achieved. The final simulation results showed that using indigenous materials for the ground floor, external walls and roof could substantially reduce the annual operative temperature by 8%, thereby increasing the predicted three months of thermal comfort in the base-case to nine months annually. Likewise, there was a 32.31%, 35.78% and 41.81% reduction in the annual CO2 emissions, cooling loads and construction costs, respectively.Originality/valueThe knowledge of indigenous materials as an alternative to conventional materials for sustainable buildings is not new. However, most of the available research is focused on achieving affordable housing. There is a dearth of research showing the extent that these indigenous materials can be used to improve indoor thermal comfort in developing countries with tropical climates such as Nigeria.

“…The first goal of NZEB is to improve the energy efficiency of a building to the ultimate level (Heinze and Voss, 2009; Musall et al , 2010; Zhao et al , 2009). The energy efficiency of any building is influenced by some passive design strategies such as thermal insulation, window glazing types, orientations, natural ventilation, window-to-wall ratio and daylighting (Onyenokporo and Ochedi, 2019; Pless and Torcellini, 2010). The effectiveness of the above stated passive design technologies on energy efficiency is influenced by the microclimatic condition of various regions of the world significantly.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of passive design strategies to achieve NZEB in the corporate facilities: the context of Bangladeshi subtropical monsoon climate

Rana

Hasan

Sobuz

et al. 2020

PurposeThis study investigates the impact and economic viability of energy-efficient building envelope and orientation for contributing net zero energy building (NZEB) and suggests optimum thermal insulation thickness, optimum wall thickness, appropriate orientation and glazing types of window in the contexts of unique Bangladeshi subtropical monsoon climate.Design/methodology/approachThe whole study was conducted through energy simulation perspective of an existing office building using building information modeling (BIM) and building energy modeling (BEM) tools which are Autodesk Revit 2017, Autodesk Green Building Studio (GBS) and eQUEST. Numerous simulation patterns were created for energy simulation considering building envelope parameters and orientations. A comprehensive data analysis of simulation results was conducted to sort out efficient passive design strategies.FindingsThe optimum thermal mass and thermal insulation thickness are 6.5 and 0.5 inches, respectively, considering energy performance and economic viability. This study highly recommends that a building should be designed with a small window-to-wall ratio in the south and west face. The window should be constructed with double glazing Low-E materials to reduce solar heat gain. The studied building saves 9.14% annual energy consumption by incorporating the suggested passive design strategies of this study.Originality/valueThe output of this work can add some new energy-efficient design strategies to Bangladesh National Building Code (BNBC) because BNBC has not suggested any codes or regulations regarding energy-efficient passive design strategies. It will also be useful to designers of Bangladesh and other countries with similar subtropical climatic contexts which are located in Southeast Asia and Northern Hemisphere of Earth.