ENERGY EFFICIENCY IN RESIDENTIAL BUILDINGS: A CASE STUDY OF 1004 FEDERAL HOUSING AUTHORITY ESTATE, VICTORIA ISLAND, LAGOS

Abstract Globally, energy consumption in buildings takes up the largest proportion of world's energy production. This consumption is more in developing countries including Nigeria and Least Developed economies than the developed worlds. Researches are therefore, currently been geared towards reducing energy consumption due to the global problem of insufficient energy needed to meet the demand and the attendant environmental issues associated with the production based largely on fossil burning. In Nigeria, consumption in buildings takes up about a third of the total electricity production with Lagos accounting for the larger percentage of the total energy production due to the fast rising population, teeming economic growth and increased rate of construction across the state. This paper thus investigates the energy consumption in residential buildings (1004 Federal Housing Authority Estate), in Lagos state. Survey analysis approach was adopted in this work. Field trips to the study area were conducted, measurements were taken and questionnaires were administered to occupants. The design features of the buildings were 248 achieved through series of demonstration works carried out in the analysis using ETTV equation. The study established that the perlite plaster has a lower thermal transmittance value (U-value) when compare to that of cement hence a better energy reducing material option in building construction. The impact of ETTV on the energy consumption of residential buildings leading to a reduction in building heat load was also established in the study

COMPARISON OF ROAD TRAFFIC ACCIDENT PREDICTION MODELS FOR TWO-LANE HIGHWAY INTEGRATING TRAFFIC AND PAVEMENT CONDITION PARAMETERS

In Nigeria, literature on the integration of traffic of pavement condition and traffic characteristics in predicting road traffic accident frequency on 2-lane highways are scanty, hence this article to fill the gap. A comparison of road traffic accident frequency prediction models on IIesha-Akure-Owo road based on the data observed between 2012 and 2014 is presented. Negative Binomial (NB), Ordered Logistic (OL) and Zero Inflated Negative Binomial (ZINB) models were used to model the frequency of road traffic accident occurrence using road traffic accident data from the Federal Road Safety Commission (FRSC) and pavement conditions parameters from pavement evaluation unit of the Federal Ministry of Works, Kaduna. The explanatory variables were: annual average daily traffic (aadt), shoulder factor (sf), rut depth (rd), pavement condition index (pci), and international roughness index (iri). The explanatory variables that were statistically significant for the three models are aadt, sf and iri with the estimated coefficients having the expected signs. The number of road traffic accident on the road increases with the traffic volume and the international roughness index while it decreases with shoulder factor. The systematic variation explained by the models amounts to 87.7, 78.1 and 74.4% for NB, ZINB and OL respectively. The research findings suggest the accident prediction models that should be integrated into pavement rehabilitation.   Keywords: &nbsp

Assessment of Calcium Carbide Waste and Calcined Clay as Stabilizer in Flexible Pavement Construction

Stabilization techniques have often been used globally to enhance properties of weak subgrade materials for flexible pavement construction. This study assessed the blend of calcium carbide waste (CCW) and calcined clay (CC) to serve as an effective stabilizer of Subgrade material (S) sourced from a section along Ota-Idiroko road. Subgrade material was initially modified with CCW in different percentage replacements by weight (0, 4, 8, 12, 16 and 20%) and the resulting blends were subjected to Atterberg’s limits test to determine the blend with optimum plasticity index reduction which would be tagged optimum subgrade lime blend (OSLB). The blend of S + 8% CCW was tagged OSLB because it exhibited optimum plasticity index reduction. The OSLB was thereafter blended by weight with CC in the following percentage replacements 3, 6, 9, 12, 15 and 18% in order to activate the pozzolanic potentials of CC for strength enhancement. The resulting blends were subjected to Atterberg’s limits, Compaction, California bearing ratio (CBR) and Unconfined compressive strength (UCS) tests with the strength specimens cured for 0, 3, 7, 28, 56 and 90 days. The results showed that OSLB-CC blends reduced the Plasticity index from14.8 to 8.4 %, Maximum dry density from 1.82 to 1.54 Mg/m3, Optimum moisture content, 23.7 to 17.9 % and increased soaked CBR, 0 to 418.2% and UCS, 201.59 to 5660.84 kPa of natural subgrade respectively. Furthermore, the blends showed great improvement with reduction in PI less than standard value of 10% and increment in standard CBR and UCS values of 180% and 1700 kPa respectively for base course material. Therefore, stabilized blends at 7 days curing period could improve the natural subgrade to subbase and base for pavement construction

EVALUATION OF VIABLE OPERATING STRATEGIES FOR PUBLIC TRANSPORT BETWEEN FUNAAB CAMPUS AND CAMP TERMINUS IN ABEOKUTA

Transportation is a live wire for national development regardless of a nation industrial capacity, population or technological development. It gives expressions to policy initiative in areas like health, education, employment, etc., and in the absence of it, these facilities would be inaccessible. Viable operating strategies for public transport between Federal University of Agriculture, Abeokuta (FUNAAB), Ogun State Nigeria Campus and Camp Terminus in Abeokuta were evolved. Traffic study was conducted for seven (7) days to determine traffic volume and peak periods (morning and evening) along the route. Questionnaires were administered to the road users to obtain factors (availability of vehicles, travel time from Camp Terminus to FUNAAB, road condition, operational cost, comfortability of the vehicle) needed to generate operating strategies. These factors were subjected to statistical analysis. The traffic volume revealed that Private cab had the highest traffic flow for a.m. peak period (8: 00 – 9: 00 am) from Mondays to Thursdays while Public cab had the highest on Fridays to Sundays, and at the pm peak period (4:00 – 5:00 pm), Public cabs had the highest traffic volume on Wednesdays, Saturdays and Sundays while the Private cabs had the highest on the rest days of the week. The analysis of the sampled population showed that public cab had the least total time travel (36.1 minutes) followed by mini- bus (37.8 minutes) while the school bus had the highest (43.7 minutes) and this justified the reason why 40% of the population choose to travel by public cab, 33% by mini– bus  and 27% by the school bus. However, for the viability of the operating strategies, more public cab and min-buses should be provided to ply the road because of their lesser travel time, also provision of more school buses because of the large number of passengers they carry per trip should be provided.     &nbsp

Structural behaviour of metakaolin infused concrete structure

This work researched into the use of metakaolin as a partial substitute for cement in concrete, metakaolin was obtained by the calcination of kaolin clay to about 700 0C Cement was replaced with the metakaolin at 0, 5, 10, 15, 20, 25, 30, and 35% at water cement ratio of 0.5. Tests such as chemical analysis, compressive strength, flexural or modulus of rupture and bond strength were carried out on the concrete samples. Chemical analysis results showed that the metakaolin is a class “N” pozzolan, while the mechanical test showed that the strength of concrete increased from 5% to 20% replacement, and the strength peaked at 20%, but decreased above this value; concrete made with metakaolin performed better than the control sample at all the percentage replacements used in this work.Keywords: Metakaolin, Calcination, Pozzolan, Chemical test, Mechanical tes

Effect of Traffic and Geometric Characteristics of Rural Two Lane Roads on Traffic Safety: a case study of Ilesha-Akure-Owo road, South-West, Nigeria

Road safety engineering involves identifying influencing factors causing traffic crashes through accident data, carrying out detailed accident studies at different locations and implementing relevant remedial measures. This study was carried out to establish relationship between traffic accident characteristics (frequency and severity) and traffic and road design characteristics on a two-lane highway. Statistical models applied in traffic accident modeling are Poisson regression, Negative Binomial regression (NB), and Zero-Inflated Negative Binomial regression (ZINB).; Traffic flow and road geometry related variables were the independent variables of the models. Using Ilesha-Akure-Owo highway, South-West, Nigeria accident prediction models were developed on the basis of accident data obtained from Federal Road Safety Commission (FRSC) during a 4-year monitoring period extending between 2012 and 2015. Curve radius (CR), lane width (LW), shoulder factor (SF), access road (CHAR), average annual daily traffic (AADT), parentage heavy good vehicle (HGV) and traffic sign posted (TSP) were the identified effective factors on crash occurrence probability. Finally, a comparison of the three models developed proved the efficiency of ZINB models against traditional Poisson and NB models. Keywords— Traffic accidents. Single carriageway, accident prediction model, road geometric characteristics

Experimental performance of LPG refrigerant charges with varied concentration of TiO2 nano-lubricants in a domestic refrigerator

This article present an experimental investigation of varied mass charges of Liquefied Petroleum Gas (40 g, 50 g, 60 g and 70 g) enhanced with varied TiO2 nanoparticle/mineral oil concentrations (0.2 g/L, 0.4 g/L and 0.6 g/L nanolubricants) in a R134a compressor of a domestic refrigerator. Performance tests investigated at steady state included: pull down time, power consumption, compressor power input, cooling capacity and coefficient of performance (COP). Analysis was based on temperature and pressure readings obtained from appropriate gauges attached to the test rig. Refrigerant property characteristics were obtained using Ref-Prop NIST 9.0 software. Results obtained showed almost equal evaporator air temperatures and reduction in power consumption for all tested nano-lubricant concentrations except at 70 g charge of LPG using 0.6 g/L nano-lubricant. Furthermore, the lowest compressor power input was found to be 21 W and obtained using 70 g of LPG with either of 0.2 g/L or 0.4 g/L nano-lubricants. At 70 g of LPG using 0.6 g/L concentration of nano-lubricant, highest cooling capacity index of 65 W was obtained while the highest COP of 2.8 was obtained with 40 g charge of LPG using 0.4 g/L concentration of nanolubricant. In conclusion, LPG-TiO2 nano-lubricant mixture works safely and efficiently in domestic refrigerators without modification of capillary tube length, but requires adequate optimization

Exergy, Exergoeconomic and Exergoenvironomic Analyses of Selected Gas Turbine Power Plants in Nigeria.

Energy supply trends as well as environmental regulations and climate change issues have made it necessary to closely scrutinize the way energy is utilized. Efficient energy utilization thus requires paying more attention to accurate and advanced thermodynamic analysis of thermal systems. Hence, methods aimed at evaluating the performances of energy systems take into account the Energy, Environment and Economics. Therefore, the first and second law of thermodynamics combined with economics and environmental impact represents a very powerful tool for the systematic study and optimization of energy systems. In this study, a thermodynamic analysis of eleven selected gas turbine power plants in Nigeria was carried out using the first and second laws of thermodynamics, economic and environmental impact concepts. Exergetic, exergo-economic and exergo-environmental analyses were conducted using operating data obtained from the power plants to determine the exergy destruction and exergy efficiency of each major component of the gas turbine in each power plant. The exergy analysis confirmed that the combustion chamber is the most exergy destructive component compared to other cycle components as expected. The percentage exergy destruction in combustion chamber varied between 86.05 and 94.6%. Increasing the gas turbine inlet temperature (GTIT), the exergy destruction of this component can be reduced. Exergo-economic analysis showed that the cost of exergy destruction is high in the combustion chamber and by increasing the GTIT effectively decreases this cost. The exergy costing analysis revealed that the unit cost of electricity produced in the plants ranged from cents 1.88/kWh (₦2.99/kWh) to cents 5.65/kWh (₦8.98/kWh). Exergo-environmental analysis showed that the CO2 emissions varied between 100.18 to 408.78 kgCO2/MWh while cost rate of environmental impact varied from 40.18 $/h (N6, 388.62/h) to 276.97$/h (N44, 038.23/h). The results further showed that CO2 emissions and cost of environmental impact decrease with increasing GTIT

Evaluation of Cement and Bitumen Emulsion on Strength Characteristics of Native South African Granular Soil as Base Course Material

Pavement rehabilitation where the material in the existing pavement is recycled in-situ with bitumen will sustain the environment with conservation of natural aggregates, reduction in noise, dust emission and traffic disruption. This study investigate the effects of a native South African granular material stabilized with cement and bitumen emulsion as a base layer in pavement construction. The material stabilized with cement-bitumen emulsion (2-3%) was subjected to Unconfined Compressive Strength (UCS) and Indirect Tensile Strength (ITS) tests for 1, 4, 7 and 28 days curing. The UCS and ITS requirement was evaluated with respect to a base layer for design traffic application of less than six million equivalent single axles. The results of UCS and ITS tests for the stabilized material showed improved strength and have the potential for use as a base course material for the design traffic. The result revealed that 2.5% cement and bitumen emulsion meets the minimum strength characteristics for the base layer. Relative to 2% cement and 2% bitumen emulsion, ITS obtained for 4 and 7 days of curing increased approximately by 24%, 41% and 24%, 53% respectively. Models for UCS in terms of ITS was developed for cement and bitumen emulsion which will make one test among the two sufficient to indicate the strength of cement and bitumen emulsion stabilized materials at the mix design level. Bitumen stabilization is a quick construction method, with lower cost than reconstruction and good for rehabilitation. Keywords— bitumen emulsion, cement, granular, indirect tensile strength unconfined compressive strength.