Introduction: Global Warming, Passivehouses and Zero Carbon

Whether or not global climate change is anthropogenic it makes good sense to save fossil fuels and reduce pollution. This requires some big changes to human behaviour in an industrialised consumer society.

We need to build an infrastructure of companies and qualified people capable of delivering the products and services required to drive the necessary changes in building methods, energy generation etc.

Zero-Carbon Solutions has been established by a group of highly qualified individuals to act as consultants, designers and suppliers of low-carbon and carbon-neutral designs, components and systems.

Transport is often held up as the main area of potential energy consumption reduction. However, there is already a large amount of misinformation on the lose in that area, e.g. that electrical vehicles pollute less than vehicles driven by fossil fuel burned in an Otto engine. The fact is that the electricity available from the UK national grid is overwhelmingly produced by burning solid fuel. Not only do the large power plants waste 65-70% of the energy they consume - typically only 30-35% is turned into electricity - but the kind of fuel used is the worst imaginable - coal. Coal is one of the fuels that yields the least amount of electricity for each ton of carbon dioxide released into the atmosphere, in short, a fuel that is completely unsuitable for electricity generation.

A normal car engine has a fuel efficiency of up to 40%, i.e. more than that of a large power plant, so running your car directly on fossil fuel results in less pollution than using an electric car which is charged (at an additional energy loss of around 20-30% from the plug to the battery) from the national grid. By using electrical cars in city centres some pollution is moved from the cities to wherever the power plants are but at an extremely high cost in additional pollution and waste of energy.

This is just one example of the prevalent and pervasive misinformation in this area.

Construction and Housing - Politics

We have chosen to concentrate on a different field from transport, however: the energy consumed by building construction and use.

The UK, in particular England, is far behind Northern Europe in terms of the quality of dwellings. A consequence is that a typical pre-1950 dwelling causes annual carbon emissions of around 7-8 tons, simply to keep the house warm. New builds are not much better, using 3-4 times as much heating energy as a modern European dwelling, which emits less than 1 ton of CO₂ annually. Over 1.5 million homes in the UK (7.5 per cent) are officially classified as unfit, leading to thousands of deaths every year. The reason for this is partly the crazy planning process, which needs to be overhauled from the top down. We use less than 30% of the land area for dwellings so there is no reason to cram the population into super-high density housing, there is no reason to build for crime.

Furthermore, the idea of planning offices throughout the country, that we should all be living in a large open air museum, must be changed. Many villages and buildings subject to conservation orders of one kind or another, have the historic and architectonic value of a potato and should be bulldozed to make way for healthy and energy-efficient modern housing!

Another reason the UK is so far behind is that the country has never been subject to a land reform: too much potential building land sits on far too few hands. The heritage organisations should be reduced in scope and size and made to sell off building land; estates should be taxed on their value, not according to the 'band' principle, as a consequence of which a 75-room mansion is taxed at the same level as a large family home; unused land within planning zones should be taxed at a particularly high rate if it is not used in accordance with the plan. This would prevent large building companies from sitting on huge swathes of building land and releasing it slowly at insane prices.

These simple and reasonable fiscal measures would serve to produce enough building land to help satisfy the demand for (affordable) housing and help to curb the problematic and unhealthy house price inflation.

Technical Introduction

In order to gain some perspective on buildings and energy consumption - and we shall stick to dwellings for the time being as opposed to e.g. industrial units - it is necessary to start to define some concepts and attach metrics to them. We will use the metric system throughout. Since few ordinary people have any pre-conceived ideas of the meaning of most of the concepts used in building physics this makes no difference - it will be new to them anyway. An important point of reference that it is good to have, though, is the size of a square meter (m²). One meter is just about three feet long, so 1m² = 9sq.ft (approximately). Consequently, one cubic meter (m³) is about 27 cu.ft. We often specify the energy consumption or energy requirement of a building as a value per m² or per m³.

As an aside, if you plan to buy a house always make sure you calculate the price per m² of living area. Don't just look at the number of bedrooms. Different sizes of rooms make a huge difference to the value you get for your money. Once you have the price per m² you have a basic metric enabling you to make comparisons between the value/price for different houses. It is not the only parameter but it is an important one and we will always quote it for the houses we sell.

In the metric SI system, work - or energy expended - is measured in Joules (J). It is the work required to produce the power of 1 watt continuously for 1 second. We are more familiar with kilowatt-hours (kWh) from our energy bills. 1kWh = 3.600.000J = 3.600kJ = 3.6MJ. We shall normally be using kWh as the unit of work. That is what ends up on the energy bill. To get a feel for it, if you forget to switch off one 100W light bulb overnight, i.e. for 10 hours, that adds 1kWh to your electricity bill corresponding to about 10p, depending on your tariff (if you had let a gas light do the work instead it would only have cost you around 3p, reflecting the fact that the power generators waste around 70% of the energy when producing electricity). Perhaps more relevant, an average UK dwelling uses more than 20.000kWh for space heating per year! For dwellings following the 2002 building regulations this has been reduced to 5.300kWh/a, already good progress. If we now relate it to the size of dwellings, we find that houses from before 1950 use about 270kWh/m²a (pronounced 270 kilowatt-hours per square meter and year - 'a' = 'annum', Latin for year) for heating purposes. If we look at the 2002 building regs we're down to a little less than 100kWh/m²a.

Now contrast this to the houses Zero-Carbon Solutions promote and deliver: a total heating bill for around 15kWh/m²a. That's right - 6-7% of the energy bill you have now if you live in a typical UK home. This kind of house is called a passivehouse, or as somebody prefer to name it, curiously using the German term for a Swedish concept, a Passivhaus. It is important to bear in mind that whereas a passivehouse is defined in technical terms, a zero carbon house is defined in fiscal/political terms that can not directly be translated into something you can order or build. Much more about that elsewhere on the site.

Another useful metric often employed on this web site is the U-value (or k-value as is used to be known). This Heat Transmission Coefficient is used to measure the quality of insulation materials, walls, windows and other building elements separating heated and unheated areas. It is extremely easy to understand, being the energy (heat) moving through an area of one square meter of a material if there is a temperature difference of one degree from one side of the material to the other (it obviously moves from the warm to the cold side - no free lunch there). Now, the degree is a Metric degree, i.e. not a degree Fahrenheit. In everyday use we measure temperature in degrees Celsius (or centigrade as some people call it), written °C. This temperature scale is defined by the freezing point of water, 0°C, and the boiling point of that very same liquid, 100°C. So, the steps (each degree) are simply the temperature difference between boiling water and freezing water divided by 100. The Fahrenheit scale has completely different steps (the degrees have a different size), so you can't directly use Fahrenheit in the energy calculations pertaining to houses, even when only temperature differences are involved.

To make things slightly more complicated but not much, instead of °C we use degrees Kelvin written simply K. The zero-point of the Kelvin scale is -273°C, and the steps (degrees) are the same size as Celsius. Hence temperature differences are the same in Kelvin and Celsius.

This lengthy discourse leads us to an understanding of a U-value in terms of metric units: it is the amount of Watts escaping through 1m² of building component for each degree Kelvin of temperature difference between the two sides of the building component. Hence, the unit is W/m²K, pronounced watt per square meter and Kelvin.

Think about it for a moment. It could be an outer wall for example. The larger the wall is, the greater the amount of heat getting lost through it. The poorer the insulation, the more heat (Watts) will escape through the same size of wall (m²) - and the colder it is outside compared to inside (K), the more heat will escape. So it all makes perfect sense. Hence, the lower the U-value is, the better the insulation, and the more money remains in your pocket while you live in the house.