Sunday, July 18, 2010

Sensory Deprivation

The UK is heading for an energy crisis in which we become over reliant on imported natural gas for our home heating and power generation. Of the 27 EU countries, the UK has the largest gas consumption of close to 100 billion cubic metres (bcm) per year. By 2015 as a result of changes in the UK electricity generating mix is going to further increase the percentage share of gas used for generating, as coal and nuclear stations reach end of life. Our gas consumption is set to rise to 120 bcm. Unless the UK can maintain a secure supply of natural gas, from friendly nations, we are heading for an almighty energy crisis.

Currently about 35% of UK gas consumption is for domestic heating. Much of our housing stock offers such poor energy efficiency that we are literally throwing away billions in our gas bills every year. The new coalition government have been advised of this and are targeting the domestic sector to reduce their energy consumption by way of better energy efficiency in the home - such as improved insulation and more efficient boilers.

In the next 40 year time frame there will be co-ordinated effort to improve the energy efficiency of our housing stock. 60% of our homes were built before 1960 and have very poor efficiency. National programmes to roll out internal and external insulation will bring our homes up to a better standard. This will help maintain gas consumption at 2010 levels, and keep our national CO2 footprint to a minimum.

Part of the problem is that older UK homes leak heat like a seive. Solid brick walls and uninsulated lofts mean that we are using at least 3 times the energy than we need to. Clearly something has to be done to curb these energy losses.

First it is important to quantify the energy consumption and losses in the older property. As part of my personal effort, I have been monitoring gas usage in my home for nearly 10 years, and noting year on year improvements.

Part of the problem is to understand the energy usage and where the heat losses occur. For this I have been working on a temperature and energy monitoring system.

In the last couple of days, I have put together a simple Arduino temperature sensing application which sends readings up to Pachube for logging and graphing.

A mental block, last weekend prevented me from converting the readings from the thermistor temperature sensors to a true centigrade reading, but in the cool light of Friday morning, I revisited the code and got the thermistor linearisation code working.

The results can be seen at my Pachube feed - I'm looking at a couple of room temperatures, the temperature at two points of my hot water tank and the outside temperature.

The standard Arduino has 6 analogue sensing channels (the Nano has an additional two ADC channels). By using Dallas 1-wire temperature sensors connected to digital pins, a much larger network of temperature sensors is possible.

At the moment, I'm monitoring my hot water tank temperature - solely becase it shows a wide range of temperature swing, which is good for testing. It would also be beneficial to monitor the inlet and exit temperatures of my solar water heating panel and in the heating season, the boiler and woodstove temperatures. Each room of the house could be individually monitored including the loft, to give a complete picture of the thermal behaviour of the house

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