Other resources

An Energy Survey of the Church Lane Building at DIT

Joseph Teehan — Fri, 22 Feb 2013 04:07:21 PST

Within the European Union, the collective governments have introduced broad energy policies in order to increase energy efficiency and improve energy performance in new and existing buildings, within each member state. The following dissertation considers energy and how energy is used within the context of global and local consumption in an extensive literature review. Where does the future lie for Ireland and its energy sources? Policies, standards and regulations associated with energy efficiency and the Energy Performance of Buildings Directive (EPBD) are defined and briefly explained. The status of how well the response from the commercial building market to Building Energy Assessment initiatives is discussed. Finally, the literature review explores some of the latest methods to improve energy consumption patterns within buildings. This literature review is intended to recognize the latest changes that may affect the Church Lane building should it undergo any improvements to its energy performance. This dissertation will include an analysis of the current condition of an existing educational facility using the Dynamic Simulation Modelling (DSM) software IES. Using this software a comprehensive analysis of the day-lighting thermal performance of the heating system, and a Building Energy Rating (BER) shall be carried out for the building. The results will be compared with the existing building’s electrical energy consumption, artificial lighting, heating requirements and current BER. Finally, energy efficient improvements and their installation costs to reduce the building’s energy consumption will be explored. This method of analyzing a building, Dynamic Simulation Modelling (DSM), will be critiqued in terms of suitability for this type of building following the process.

A Methodology for Development of a More Parsimonious Building Energy Asset Rating Method for Energy Demand Reduction Targeting

Daire Reilly et al. — Wed, 31 Oct 2012 08:10:23 PDT

In accordance with national and European policies, the provision of financial assistance to residential energy consumers has led to a greater awareness of and interest in energy retrofit technologies. However, at present Irish energy consumers have no appropriate advice on the future performance of retrofit options available to them. This is a significant limitation to decision making and technology uptake, since this group need to know whether their investment is likely to be worthwhile.

The asset rating methodology developed for the certification of energy performance of buildings is the current industry standard of prediction of energy demand and post retrofit performance. The methodology is tedious and may not be viable for ESCos to send trained assessors to residential dwellings while residential customers do not possess the technical knowledge to complete the survey of their own dwelling.

This research investigates if the asset rating procedure can be simplified to permit development of simpler models, which would allow quicker and easier assessment of the energy performance of residential dwellings.

An asset rating model was created in excel. The Irish housing stock was simulated using a sample data set and Monte Carlo techniques. The model was simplified in stages by systematically removing and parameterising input variables from an initial list of 50.

The results of these test methods are presented and should be consulted by policy makers, ESCos and private bodies who wish to create a simplified asset rating type model with known error margins for the prediction of dwelling energy performance.

Flood Routing in Natural Channels Using Muskingum Methods

Safa Elbashir — Fri, 20 Apr 2012 02:25:05 PDT

The accuracy of flood routing is an important subject for research in hydrology and hydraulics. Accurate information of the flood peak attenuation and the duration of the high water levels obtained by channel routing are of most importance in flood forecasting operations and flood protection works (Subramanya, 2008). This study implements two hydrological methods for channel routing, the basic Muskingum and the constant coefficient Muskingum-Cunge methods on the River Brosna, Co. Offaly in Ireland. Previous researches have reported the simplicity and applicability of these methods on most natural streams within certain limits. These limitations are encountered in the River Brosna where the available outflow data included a significant degree of error which makes it difficult to use for comparison and modelling purposes. Moreover, other factors influenced the implementation and the accuracy of these methods, in particular the backwater effects due to a weir located nearly four kilometres upstream the selected reach and the gradient of the channel which was very small (0.00047) to dampen the error in the routing procedure. This error is found to be greater when using a minimum time increment in the routing calculation. The results of this study showed that the hydrological methods failed to simulate the outflow hydrograph in the selected reach. Determining the models parameters was not possible by using the basic Muskingum method, whereas, the constant coefficient Muskingum-Cunge method calibrated some negative values for the attenuation, which contradicted the diffusivity of the flood wave and confirmed the significant effect of the weir located downstream the river. The conclusion is that an alternative method is needed to account for the factors that these methods neglect.

A remote interrogation system for monitoring concrete performance exposed to environmental action

Niall O. Holmes — Thu, 19 May 2011 08:30:09 PDT

The performance of the surface zone of concrete is acknowledged as a major factor governing
the rate of deterioration of reinforced concrete structures as it provides the only barrier to the
ingress of water containing dissolved ionic species such as chlorides which, ultimately,
initiate corrosion of the reinforcement. In-situ monitoring of cover-zone concrete is critical in
attempting to make realistic predictions as to the in-service performance of the structure. To
this end, this paper presents developments in a remote interrogation system to allow
continuous, real-time monitoring of the cover-zone concrete from an office setting. Use is
made of a multi-electrode array [19] embedded within cover-zone concrete to acquire
discretized electrical resistivity and temperature measurements, with both parameters
monitored spatially and temporally. On-site, instrumentation, which allows remote
interrogation of concrete samples placed at a marine exposure site, is detailed, together with
data handling and processing procedures. Site-measurements highlight the influence of
temperature on electrical resistivity and an Arrhenius-based temperature correction protocol
is developed using on-site measurements to standardize resistivity data to a reference
temperature; this is an advancement over the use of laboratory-based procedures. The testing
methodology and interrogation system represents an additional technique which could be
used for intelligent monitoring of reinforced concrete structures.

Performance of Elotex®Copra900 as a Corrosion Inhibitor

Niall O. Holmes — Thu, 19 May 2011 08:30:06 PDT

Corrosion inhibitors as cement additions consist of powders or solutions that are added to concrete when mixed to prevent or delay corrosion. This paper presents an early-age evaluation of a new corrosion inhibitor, namely ELOTEX^®COPRA900 following a corrosion and durability study on concrete samples with different cementitious materials.

A comparison of the corrosion inhibition properties of ELOTEX^®COPRA900 against a well known and established corrosion inhibitor on the market, namely Calcium Nitrite and a control with no corrosion inhibitor product. Calcium Nitrite works by increasing the threshold of chlorides required for corrosion to begin. ELOTEX^®COPRA900 on the other hand surrounds the embedded reinforcement with a secondary protective layer that is activated when the passive oxide layer also surrounding the reinforcement breaks down due to the initiation of the chloride corrosion mechanism. The aim of this project is to evaluate ELOTEX^®COPRA900 in concrete mixes exposed to accelerated corrosion conditions including CEM I, PFA and GGBS cements.

The results from this experimental programme have demonstrated that ELOTEX^®COPRA900 is an effective corrosion inhibitor. The results have shown, in every case, that concrete containing ELOTEX^®COPRA900 are less penetrable to chlorides than those without. The addition of ELOTEX^®COPRA900 has been found to alter the pore structure so it becomes discontinuous and a capillary blocking effect occurs. In the case of those concretes containing PFA and GGBS, it was found that ELOTEX^®COPRA900 made no significant improvement to the corrosion and durability performance.

However, one noticeable effect of the inclusion of ELOTEX^®COPRA900 in the concrete mix is the consistent reduction in the compression strength. This has found to be due to the hydrophobic layer that forms on the cement particles which affects the hydration and strength development. However, it is expected that this will only affect low strength concretes which are uncommon in challenging exposures. Also, the quantity of ELOTEX^®COPRA900 used here (4% by mass of cement) would be seen as on the higher side of what would typically be recommended. Reducing the volume of ELOTEX^®COPRA900 would therefore reduce these effects of loss in compressive strength.

Moisture movement in concrete during drying

Niall O. Holmes — Thu, 19 May 2011 08:30:02 PDT

Probalistic analysis of highway bridge traffic loading

Colin C. Caprani — Wed, 03 Dec 2008 08:09:47 PST

Many bridges of the world’s highway networks have been in service for decades and are subject to escalating volumes of traffic. Consequently, there is a growing need for the rehabilitation or replacement of bridges due to deterioration and increased loading. The assessment of the strength of the existing bridge is relatively well understood, whereas the traffic loading it is subject to, is not as well understood. Accurate assessment of the loading to which bridges may be subject, can result in significant savings for the highway maintenance budgets internationally. In recent years, a general approach has emerged in the research literature: the characteristics of the traffic at a site are measured and used to investigate the load effects to which the bridge may be subject in its remaining lifetime.

This research has the broad objective of developing better methods of statistical analysis of highway bridge traffic loading. The work focuses on short- to medium-length (approximately 15 to 50 m), single- or two-span bridges with two opposing lanes of traffic. Dynamic interaction of the trucks on the bridge is generally not included.

Intuitively, it can be accepted that the gap between successive trucks has important implications for the amount of load that may be applied to any given bridge length. This work describes, in quantitative terms, the implications for various bridge lengths and load effects. A new method of modelling headway for this critical time-frame is presented.

When daily maximum load effects (for example) are considered as the basis for an extreme value statistical analysis of the simulation results, it is shown that although this data is independent, it is not identically distributed. Physically this is manifest as the difference in load effect between 2- and 3-truck crossing events. A method termed composite distribution statistics is presented which accounts for the different distributions of load effect caused by different event types. Exact equations are derived, as well as asymptotic expressions which facilitate the application of the method.

Due to sampling variability, the estimate of lifetime load effect varies for each sample of load effect taken. In this work, the method of predictive likelihood is used to calculate the variability of the predicted extreme for a given sample. In this manner, sources of uncertainty can be taken into account and the resulting lifetime load effect is shown to be calculated with reasonable assurance.

To calculate the total lifetime load effect static load effect plus that due to dynamic interaction), the results of dynamic simulations based on 10-years of static results are used in a multivariate extreme value analysis. This form of analysis allows for the inherent correlation between the total and static load effect that results from loading events. A distribution of dynamic amplification factor and estimates for a site dynamic allowance factor are made using parametric bootstrapping techniques. It is shown that the influence of dynamic interaction decreases with increasing static load effect.