Energy Rating for Residential Buildings

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Table of Contents

Abstract
Introduction
Energy Assessment Tools
Measuring the Energy Rating Metrics in a Building
Developing a Standard Method of Measuring Energy Ratings
Recommended improvements for Measuring Energy Performance
Recommendations
Conclusion
References

Abstract

Increased human population has led to uncontrolled exploitation of natural resources leading to destruction of the ecosystem. Forests and wetlands have been cleared to create land both for settlement and agriculture. By clearing the forests, the world is witnessing an increased carbon emission into the atmosphere, leading to the destruction of the ozone layer (Douglous, 2006). The number of residential houses has been increasing proportionally to meet the increasing population for settlement purposes. The increased residential unit has increased the demand for energy and consequently the level of greenhouse gas emission. In Australia for example, there are about eight million residential homes, which use 13% of the total energy and emit 10% of the greenhouse gases (Douglous, 2006).

Governments world over are funding mechanisms that will help reduce the number of greenhouse gases emitted by the use of regulations and incentives. The main hurdle in saving on energy and reducing the emission of greenhouse gases into the atmosphere s to quantify the energy consumed. We must quantify our consumption before we can determine the ways to save and reduce emissions. With the hard economic times, building designers are conscious of the need to come up with buildings that are efficient on energy use in order to reduce the energy bills (Lapkin & Constable, 2008).

This paper looks at the energy ratings in residential houses, the limitations in the methods used to measure the energy metrics,d possible improvements that should be applied to improve the measurements. The report is divided into sections, the first section looks at the tools of measurement. The second part is dedicated to the procedure of measuring the energy performance of a building, the shortcomings, and suggestions to reduce the shortcomings.

Introduction

The Australian government has bebeenhe forefront to help the citizens reduce their energy consumption. A number of incentives and financial support are already in place to support this course. In this report, the writer demonstrates that the energy rating metrics on building energy efficiency are not always true; it also explains how the energy metrics are measured and suggests changes that should be adopted to improve the measurement of energy rating metrics.

There are several tools for measuring the energy performance of a building but all lack standardization, making it difficult to get reliable data from the measurement. This report will look at the various tools used in the measurement of building energy performance and the shortcomings in the tools of measurement. The report also looks at the measuring procedure and suggests the possible improvements that are needed to make the measuring tools reliable.

Energy Assessment Tools

There has been a growing concern over the lack of connection between the tools used to measure the energy efficiency of buildings. The variations in the various tools used to rate the buildings’ energy efficiency have been noted in the parameters that each tool focuses on to rate a building in terms of energy efficiency. Some tools focus on the products used in the construction of the building, others use them to look at the buildings’ occupants. There are still other tools that focus on the assessment of a building’s life cycle as others consider only the efficiency of the heating and cooling processes during its operation (Joshi & Kumar, 2012).

Different tools of measurement of the metric energy rating as explained focus on different measurement parameters. With these differences and the proponent of each tool trying to stick by the working principles behind their tool, it’s becoming difficult to identify the most reliable tool of measurement. The tools are categorized either as assessment tools or rating tools. Measurement tools help in the determination of a building’s quantitative performance for design purposes (Ebert, 2005). Rating tools on the other hand provide information that helps in the comparison of a building’s energy performance in relation to the set standards.

The national home energy rating scheme works with three main software tools that are based on the predictive performance approach. The tools include; Accurate, BERSPro, and FirstRate5. The software model and rate a building’s thermal performance in relation to the standards of star bands. Another software; NABERS Home is used to determine the actual environmental performance of the building during its operation (Levy, 2011). It has now emerged that because of the many tools of measurement, there is a lack of consistency in the methodology and even the results obtained. The results obtained are often market-driven and therefore biased. There is a need to develop tools that will provide reliable results that are consistent with climate changes in the country. The tools should take into consideration all parameters including; the weight of the building, building use, and the residence behavior patterns.

Greenhouse gas emissions are regarded as critical in the measurement and evaluation of energy metrics. Besides, the embodied energy as well as the peak load energy is part of the evaluation parameters. This is an indication that all measurement tools are drifting away from presenting energy in terms of joules and watts to the output of carbon per floor area of the building. Proposals of measuring the energy efficiency in terms of metrics of carbon emission per floor area are also being explored (Hunn, 1996). The current energy efficiency ratings seem to be mainly for compliance with the codes that are contained in the regulations but are not effective in helping to obtain accurate results (McDowall, 2008).

One very important parameter that has been ignored in the tools of measurement is the relation between cooling and climate. The tools only recognize the relationship between climate and heating, expressed in terms of heating degree days. The standards set out in the tools are more lenient to situations of harsh weather but do not apply the same measure to benign climates. This is justified on the basis that if the standards are made uniform, then the residents in harsh climates would be forced by the standard enforcers to meet higher performance standards (Awbi, 2010). “The Building Environment Industry Innovation Council” supports measurement tools that consider the modeling of energy ratings especially for new buildings (Awbi, 2010). The council also supports the “normalized measurement per floor area”, which is in line with the United Nations Convention on Climate Changes (Miller, 2006). The approach also differentiates the carbon metrics for residential and commercial buildings and can be applied both for new and old buildings.

There is also a problem as regards training and accreditation of energy efficiency assessors. Since there is a difference in state rating schemes, yet assessors are trained on a uniform curriculum, assessors find themselves limited to work only in particular areas where the standards are in line with their skills and knowledge. Although there is only one umbrella organization for the “home energy rating assessors,” there is a lack of uniform distribution of training tools across the states (Means, 2011). Each state as a result has its own assessor registration system. There is a need to develop an administrative system at the national level that should run the design of rating tools in line with the standards.

Measuring the Energy Rating Metrics in a Building

The real estate market in the current era is shaped by among other factors efficient energy use. A building’s energy efficiency is based on the ratings given to the building by the home energy assessors based on the compliance codes (Bose, 2010). In order to come up with the ratings, the assessors carry out a simulation of the building based on the information provided on the plans and the building specifications. Assessors can also do a simulation of a building with similar features as the one in question and make a comparison. Some of the methods used for energy efficiency assessment include; home energy rating system and ASHRAE 90.1 (Santamouris, M 2012). The methods provide a way of modeling an energy model that is used to predict the energy efficiency of a building.

At various instances of the building life cycle, measurements of a building energy performance are taken and analyzed for various reasons. Two levels of “performance metrics are used right from the planning stage of the building to its operation life” (Bose, 2010). The first level looks at the building performance and derives data from monthly and annual utility bills (Daryl & Harvey, 2010). The second level looks at a comprehensive breakdown of energy utilization and derives its data from hours monitoring of the meters. At the second level, the performance indicators are higher than the first level as more complex information is put together, showing the trends in energy consumption by the building.

The performance metrics of a building are usually aligned with the goals and objectives of the building during design. It is important therefore to know the performance objectives of a building in order to assess its performance metrics. The main objective in the evaluation of a building’s performance is usually to reduce energy consumption during its operation. The “goal setting is usually to reduce energy consumption by 70% in relation to the compliant code set in ASHRAE 90.1” based on normal weather conditions (Bordart, & Eyrard, 2011).

Developing a Standard Method of Measuring Energy Ratings

In order to develop an accurate measuring tools, there is need to have benchmarks from which the accuracy of the tool can be compared. First, performance should be linked to the intended use of the design. Building usage largely determines its metric performance and should be considered in developing the tool of measurement. The second benchmark item is other similar buildings in the same location. It is common sense that buildings of same magnitude, usage and design within the same location use averagely the same energy. The building performance rating systems should also be considered in developing an accurate tool of energy rating (Woodcock & Francis, 2008). The rating system provides standards within which a tool should be developed. The rating tool should be based on the current economic and energy efficiency strategies. New strategies are continuously being developed and lodged into the market. These strategies should form the basis of reference in developing a measuring tool. Finally,” the tool should have long-term performance reports that enable maintenance staff establish an energy performance trend” (Bose, 2010).

The measurement tool needs to analyze different energy aspects of a building. The first energy aspect is the interior lighting system, which can be applied both in existing and proposed buildings. Results for this feature is derived amount of light energy consumed by the building, usually on an annual basis, as well as the energy saved from residency activities and daylight controls. It is also important to consider the amount of energy consumed by the building directly in the lighting process as a percentage. This approach compliments measurement protocols that do not consider a comprehensive analysis of performance metrics.

Source energy and emissions from the use of energy should also be considered in developing a measurement tool. This provides “a fuel and emission factor that is used to calculate the primary energy” (Deru, & Torcellini, 2007). The emission factor is determined for electricity, fuels as well as the heating energy used up by the building. Fuel and emission factor used in this calculation is either as used to deliver and process the energy at the power station or to deliver the energy right to the building. One also needs to develop a standard geometry in order to evaluate energy use in a building. A building geometry is characterized by its energy metrics, which is used to work out the energy performance metrics and to perform an energy simulation procedure.

Developing an energy simulation model that is compliant with the code of regulation is an important part of a measuring tool (Bennett, 2012). The simulation models should be linked to the design of the building as well as the operation status of the building after and during construction.

Recommended improvements for Measuring Energy Performance

Currently there no standardized methods for measuring energy performance in the building industry. This makes it difficult to determine the actual energy performance of a building and make relevant predictions on other buildings (Belusko & O’Leary, 2010). Standard metrics are important for energy performance related research and assessing the energy needs of a building. A standardized metric should be in agreement with the “performance metrics, case reference and method of reporting” (Bose, 2010). In measuring the energy performance, this report recommends the following guidelines.

The simulation of the design roadmap should be based on benchmarked buildings in order to ascertain the beginning point of the energy simulation. The energy simulation throughout the building process should have only one goal; to save energy. After the simulation process, there will be need to validate the technologies used in the construction of the building. This is done through a monitoring and evaluation process to examine the ability of the design technologies in existing buildings. Monitoring and evaluation process at this stage should be conducted in relation to the laid down procedure for carrying out research on performance metrics (Prahl, 2000).

Optimization should be considered in the evaluation performance metrics as well. At this level, data from the benchmarks, baseline procedures and the performance metrics from the operations of the entire building are considered. Besides, fuel and emission factors can also be part of the optimization data (Belusko & O’Leary, 2010). There is need to develop a database of buildings with high performance metrics to serve as benchmarks in future designs.

Recommendations

There are still some areas that need to be explored further, to create more understanding in the subject. The first of this is the zero energy buildings. These are buildings that use very low energy, though with high demand of the same; causing a problem on the utilities. There is so far very little understanding regarding the impact of these buildings on the national grid system as well as the utility companies. There is also lack of information on the effect of energy producing buildings on the primary energy and the emissions (Verwer, 2010). Future research should focus on the effect of zero energy buildings on the national grid system so as to provide guideline information on the demand can be managed through regulation and storage.

It is important to track the energy performance of a building throughout its life span. Often the energy performance expectation at the design stage does not remain consistent with time. There is lack of proper methodologies to track and measure the energy performance of a building in its life cycle. There is need to develop methods that are simple for tracking the building’s energy performance during the course of its operation. Performance rating methodologies should also be standardized. Currently, there are numerous performance rating methods which do not give same results when each of them is applied to rate the same building. Most rating methods available require a professional know-how to interpret. It is therefore important to develop methods that are user friendly in comparing the results with existing ones. A web-based simulation application can for example provide one with information on code compliant buildings and strategies that can be used to improve energy use in a building (Verwer, 2010).

Information on life-cycle analysis is also important; research points out that buildings consume close to one third of the primary energy as well as up to 70% of electricity. Besides, the buildings also use a lot of natural resources; life cycle analysis provides an overview on how to evaluate different features of a building. Evaluation of the features of a building helps in the design of an eco-friendly building, the life cycle analysis provides information to determine the environmental impact of the building. As a final recommendation, there is need to develop an energy simulation system for existing buildings as the current simulation is only relevant at the design stage.

Conclusion

This paper has demonstrated that the building industry requires more research work in energy performance measurement of a building. There exist numerous methods which are to some extent confusing and difficult to use by non professionals. Standard and reliable tools of energy performance measurement are needed to ensure consistency in the results obtained during the measurement. Without standardized tools of measurement, it would be difficult to belief the energy ratings that assessors give to various buildings after their assessment (Woodcock & Francis, 2008). If the suggestions recommended in this report are adopted, a more reliable tool of measurement can be attained for use in rating buildings in terms of energy efficiency. Opponents of the various tools of measuring the energy efficiency of buildings point out that the tools are more inclined to making the building appeal to the market rather than provide the actual energy rating of the building.

References

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Verwer, P 2010, pulping the RIS fictions, The Property Council of Australia (PCA). Web.

Woodcock, M & Francis, D 2008, Team Metrics: Resources For Measuring And Improving Team Performance. Massachusetts: HRD, Press Inc.

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