A Guide to Energy Management in Buildings

Douglas Harris

• Publisher: Routledge
• Year: 2016
• ISBN:
  9781317310440
• Edition: 2
• Topic: Technology & Engineering
• Subtopic: Construction & Architectural Engineering
• Index: Technology & Engineering

This new edition of A Guide to Energy Management in Buildings begins by asking why we need to control energy use in buildings and proceeds to discuss how the energy consumption of a building can be assessed or estimated through an energy audit. It then details a range of interventions to reduce energy use and outlines methods of assessing the cost-effectiveness of such measures.

Topics covered include:

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• where and how energy is used in buildings

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• energy audits

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• measuring and monitoring energy use

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• techniques for reducing energy use in buildings

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• legislative issues.

And new in this edition:

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• the cooling of buildings

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• fuel costs and smart metering

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• and education and professional recognition.

It provides a template for instigating the energy-management process within an organization, as well as guidance on management issues such as employee motivation, and gives practical details on how to carry the process through. This book should appeal to building and facilities managers and also to students of energy management modules in FE and HE courses.

1
Background

The energy problem

The importance of energy to a country’s economy and the impact of energy use on the environment are matters which have received vastly increased attention in the last few years. The problem is often stated as an energy ‘trilemma’, which is defined as the need to

• improve security of supply
• reduce energy costs to consumers and businesses
• reduce carbon emissions to minimise the increase in global average surface temperature.

Climate change is now widely acknowledged to be a product of man’s profligate use of fossil fuels, and it is well known that there is an urgent need to cut our fossil fuel consumption substantially over the next few years. Approximately 50 per cent of our energy use, and carbon dioxide (CO₂) emissions into the atmosphere, are from the use of energy for heating, cooling and lighting buildings; 25–30 per cent is used in transport, while the remainder is used for industrial processing. At the Kyoto summit in December 1997, the UK made a voluntary commitment to reduce CO₂ emissions by 20 per cent by the year 2010, and other countries made similar commitments to reduce their use of fossil fuels. While some countries made substantial cuts and exceeded their targets, others failed to meet their commitments; in emerging economies such as China, there have been sharp increases in emissions in recent years. More ambitious recent targets require a reduction of 60 per cent in carbon emissions by 2050, and the 2015 Paris Agreement heralds a new phase in global action to tackle climate change.

In addition to global treaties regarding carbon emissions, building regulations and codes of practice in the UK and many other countries are becoming increasingly strict concerning energy use. In Scotland, for example, the latest building regulations (2015) have been amended to produce a 43 percent reduction in CO₂ emissions for newly constructed domestic buildings relative to 2010 figures.

As buildings account for about 32 percent of the world’s energy use (nearer 40 percent of primary energy use if embodied energy for construction is included), it is clear that reducing energy consumption in buildings can make a major contribution to lessening carbon emissions to a meaningful degree, and good management of energy use in buildings is acknowledged as an important aspect of sustainable development.

Sustainability

Minimising energy use in buildings is an important aspect of sustainability. In the Building Research Establishment Environmental Assessment Method (BREEAM) of assessing the environmental impact of buildings, having low carbon emissions is important in achieving a high sustainability rating for a building. Much BREEAM activity is directed at new-build and the BREEAM process can help steer design teams towards more sustainable solutions, but consideration of some of the issues fundamental to BREEAM and other assessment methods used around the world can also guide us towards better approaches to the refurbishment of existing buildings. A notable example is material use: assessment methods give credit for reusing and recycling materials, since they result in lower raw-material use and reduced embodied energy. Analysis of the embodied energy in a building may also help us decide whether to retain a building or to replace it altogether. The embodied energy of a large building may be substantial, and it is often better to keep the frame of a building and refurbish it in a low-energy way, than to demolish it and replace it with a new one. Valuable architectural features and the significance of the building as part of the urban fabric are further qualities that may argue for its retention, although they are harder to quantify than embodied energy.

The importance of this is reflected in the BREEAM environmental assessment method for buildings, of which energy consumption is a major constituent: over 30 per cent of the credits in this system are related to energy efficiency. It has been estimated that office buildings in the UK alone are losing £7 million a day through wasted energy. Improved standards are continually being required of new buildings – changes to Building Regulations Part L in 2010 meant that carbon emissions had to be cut by 25 per cent compared with 2006 levels. Carbon reduction is no longer something that is just talked about, it has become an integral part of the building manager’s job, and people are now scrutinizing carefully their energy consumption and carbon emissions, at home and at work. The changes required to ensure continued improvements in this area demand a huge change in our attitude towards energy use and generation methods, and even with improvements in demand management we will need to generate 30–40 per cent of energy from renewable sources – amounting to an increase of about 1200 MW annually.

Reducing the impact of climate change by lessening our reliance on fossil fuels is only one of the reasons for wanting to lower our consumption of energy in buildings. Although global economic growth has not been even, and indeed in some places has been negative, in recent decades countries such as China have been expanding their economies rapidly, and with this expansion there has been an increased demand for energy, much of it provided by fossil fuels such as oil, coal and gas. This brings with it another aspect of the energy problem, that of continuity of supply of fossil fuel; fuel reserves are dwindling, and many observers estimate that oil production is already past its peak. If demand continues to soar while supply falls, prices will inevitably escalate at a rapid rate, leading to severe economic and social problems. Thus, for economic and environmental reasons, reducing energy use in buildings is imperative. Prior to a continued fall in oil prices in the last year or two, increases in oil and gas prices raised public awareness about the cost of energy. In the UK gas price increases of 25 per cent in less than a year led both domestic and business users to place a greater emphasis on energy efficiency, but during the writing of this book there was a period of increased oil production in Saudi Arabia and other Gulf states, which resulted in significant reductions in the oil price. Although there will always be periods of fluctuating oil prices, the long-term trajectory must inevitably be upwards. Many countries rely for their fuel supplies on increasingly expensive imports, therefore the need to reduce this reliance is a further driving force behind energy management. The impact of current legislation on energy efficiency, the use of new materials and techniques for utilizing renewable energy, and the adoption of more energy-conscious design, mean that most new buildings will consume much less energy per square metre than the majority of those already existing. Initiatives such as the Code for Sustainable Homes and the Passivhaus standard help guide architects towards low-energy solutions, although the UK Government came in for much criticism when it scrapped plans to have all new housing zero carbon by 2016.

The long-term effects of climate change will result in slightly lowered heating loads and increased cooling loads, but these are unlikely to have a significant effect on energy use. Energy consumption in existing buildings is the most important factor, as in most developed countries the rate of replacement of old buildings with new ones is very low (about 1 per cent per year) and the time scale for substantial reductions in CO₂ emissions is therefore very long (see Figure 1.1). The use of passive techniques such as greater thermal mass and better use of solar gains, which help to keep consumption down in many new buildings, is only applicable to a fraction of older buildings; in order to achieve a more rapid reduction in CO₂ levels, lowering energy consumption in existing buildings is consequently of major importance. Governments worldwide are instigating measures to improve sustainability throughout all areas of economic activity, and energy efficiency in buildings is an essential element of all these initiatives.

Against this background, the purpose of energy management is to analyse where energy is wasted in buildings and identify cost-effective solutions. While many techniques can be applied to both new and existing buildings, the contents of this book are aimed mainly at improving buildings already in use.

Figure 1.1 Effect on CO₂ emissions if every new building emitted at only 50 per cent of current levels without reducing energy use in existing buildings

Energy use in buildings

In some respects the statistics paint a fairly gloomy picture, but they do highlight the need for urgency in applying carbon-reduction measures. Energy management as described in this book is largely concerned with demand-side management: that is, reducing the demand for energy in existing buildings by improving the fabric, plant and management of the building. While the use of renewable sources of energy such as photovoltaics (PV) helps to supply that demand with reduced carbon emissions, the focus here is on reducing demand at the outset. Once the demand is lowered, then more carbon-efficient sources of supply can be considered.

Domestic

Within developed countries in Western Europe, between 30 and 60 per cent of primary energy is used in buildings, chiefly to provide heating, cooling and lighting. In the UK, approximately half of ...

Table of contents

• Cover
• Title
• Copyright
• Contents
• List of illustrations
• 1 Background
• 2 Aspects of building energy use
• 3 Energy audits
• 4 Techniques for reducing energy consumption
• 5 Instrumentation and measurements
• 6 Organization and implementation
• 7 Legislation and grants
• 8 Controls and building management systems (BMS)
• Case study 1: an office building with medium-level glazing
• Case study 2: conversion of a traditionally built dwelling to office use
• Appendix 1: estimating energy consumption using degree days
• Appendix 2: additional data and calculations
• Selected bibliography
• Index