In recent decades, total energy consumption has risen significantly: in 1971 it stood at 97 million tonnes of oil equivalent (toe), and by 2002 consumption had grown to 135.7 million toe, an overall increase of around 40%. Of these 135.7 million tonnes, 40 million tonnes are accounted for by the civil sector (compared with 30 million in 1971 ). More than half of this consumption is covered by natural gas. These facts clearly explain why, for almost twenty years, industry across Europe has been working to develop and introduce technologies that reduce the energy consumption required for industrial activity and everyday life.
These efforts are directed in two ways:
• towards limiting energy waste
• towards introducing technologies that convert energy more efficiently
A great many measures have been introduced in the field of energy saving:
• more or less simple devices, such as thermostatic radiator valves,
• sophisticated temperature control devices, such as weather compensators or PID control systems,
• far more "labour-intensive" solutions, such as replacing old window frames, replacing old boilers with condensing boilers, insulating walls and so on.
Any increase in effectiveness immediately raises the question of efficiency. In energy conversion, thermodynamic efficiency is expressed as the ratio of useful energy (work) obtained to the amount of energy supplied. As is well known, efficiency can be expressed as an absolute value from 0 to 1, or as a percentage. Specifically, for a heat source this parameter is given by the ratio of the heat output transferred by the boiler to the heat transfer medium to the heat output generated from the volume of fuel supplied.
In the case of a heating system, the efficiency of a particular solution is determined over a given period during which the system was in operation, so for a whole year it is the heating season that is taken into account.
Defining the period over which the analysis will be carried out is therefore an important part of the assessment: naturally, it is not limited to simply counting the number of days on which the system was running. As is well known, this factor depends on the climatic conditions at the place where the heating system is installed, because they determine:
1. the length of the heating season
2. the consumption curve of the heating system
With the latter, it should be remembered that fuel consumption varies (and significantly so) both with the time of year and with the geographical location. It was therefore appropriate to introduce the concept of the consumption curve.
Another important aspect is the layout of the heating system: in energy terms, the operation of the system can be described as a sequence of transformations, that is, conversions of one form of energy into another. It is clear that the conversions in which gas (or, more generally, fuel) is turned into useful heat for warming a given space are not "airtight" in energy terms.
Using the legislation in force, designers must pursue the following aims:
1. to reduce the amount of energy required as far as possible
2. to reduce losses as far as possible
3. to recover lost energy and return it to the heating system
It follows that all these factors must be taken into account when designing a heating system.
The analytical expression of relative efficiency will also be more complex. This is reflected both in energy-saving legislation and in technical standards.
The Kyoto Protocol
an international agreement on reducing emissions
Historically, the most significant step the international community has taken on energy saving is the Kyoto Protocol. It supplemented the United Nations Framework Convention on Climate Change and, at the same time, the international agreement on combating global warming. It was signed at the conference in Kyoto in December 1997. The treaty entered into force on 16 February 2005, three months after its ratification by Russia on 4 November 2004.
Basic provisions
Under the provisions of the protocol, the countries that chose to ratify it undertake to reduce their emissions of carbon dioxide, methane, nitrous oxide, HFCs and PFCs – the greenhouse gases – by 2012 (by at least 5% of 1990 emissions). Where emissions of these gases fall short of or exceed the limits, the parties to the agreement have undertaken to take part in "trading", which involves selling quotas to or buying them from other countries. If the provisions of the Kyoto Protocol are implemented in full, the average global temperature is expected to fall by between 0.02 °C and 0.28 °C by 2050. The Kyoto Protocol is a legally binding agreement under which industrialised countries are obliged to reduce total greenhouse gas emissions by 5.2% by 2012 compared with 1990. It should be noted that, given the level of reduction in greenhouse gas emissions already expected beforehand, the planned level is as much as 29%. The individual reduction levels range from 8% for the European Union, 7% for the United States, 6% for Japan and 0% for Russia, to permitted increases of 8% for Australia and 10% for Iceland. The Kyoto Protocol also supplements the provisions of the United Nations Framework Convention on Climate Change, adopted earlier at the Earth Summit in Rio de Janeiro in 1992. This means that certain legal restrictions can be changed only by those countries that have already ratified the above protocol. Annex 1 to the UNFCCC lists mostly the highly developed countries of the world, which bear moral responsibility for the current situation.
The protocol also reaffirms the principle that developed countries are obliged to support the technological development of the least developed countries, along with climate studies and projects aimed chiefly at developing alternative energy sources such as wind, solar or nuclear power. Such environmentally friendly investments in poorer countries benefit the highly developed countries, because they allow them to earn the right to further greenhouse gas emissions.
Non-compliance
Countries that continue to produce more greenhouse gases after 2012 than their limits allow will have to meet their obligations in the following period, with their permitted emission quotas reduced by 30%.