Warm as toast

So far the house has been cosy warm, an early indication that having lots of north facing windows and good insulation makes a big difference.

The picture shows the midday sun streaming into the family room heating the insulated floor slab.

We haven't had any really cold days yet but early indications are we will be very comfortable.

We have added another couple of channels to the temperature data logging; the floor slab and the roof space.
Above is the graph of the past 7 days.
Blue is the inside temp; averaging about 21, max about 24 and min about 18 deg.
Green is the floor slab, hovering around 19 to 20 deg.
Cyan in the temperature in the roof space; peaking at almost 35 deg on the sunniest day the dropping to the same as the outside temp (red) during the night.

The green green grass of home

The new grass has really got established thanks to the mild wet weather we have been having. June mowed it last weekend for the first time.

The logging has begun

No, not with a chainsaw.
We have begun recording temperatures,  two sensors to begin with; inside and outside, but there are many more to come. Future sensors will record the temperature of the floor slab, attic, solar hot water collectors, under floor water heating system, wetback etc.
The underfloor heating won't be commissioned this winter so we will have a base year of data to compare the improvements it makes

The top line is the inside temp; the peaks near 30 deg were sunny days with the house closed up; lots of yummy solar gain.

For the technically minded: I am using the Maxim 1-Wire devices to record the temperature. These sensors are connected together using 1 wire plus a return wire, so 2 wires really. Each sensor has its own unique address allowing them all to be connected in parallel so wiring is easy.
I'm using DS18S20: 1-Wire Parasite-Power Digital Thermometer sensors connected to a DS9490: USB to 1-Wire/iButton Adapter which interfaces the sensors to the old PC I'm using to record the data. I chose 1-Wire products because they are cheap and easy to use. The sensors cost about $8 each and the USB interface about $60. More data on these devices can be found at http://www.maxim-ic.com/products/1-wire/

The best program I could find was LogTemp, although there are numerous others available and best of all most of them are free. I chose LogTemp because it was simple, does everything I require and much much more and runs in windows (many are for Linux). The setup was very sinple connect sensor to USB interface, load drivers for the USB interface from here http://www.maxim-ic.com/products/ibutton/software/tmex/index.cfm and down load LogTemp from here http://www.mrsoft.fi/ohj01en.htm.

The power consumption of the computer used to record the data is a consideration because it needs to run 24/7. Ideally I would use an old laptop set to its lowest power settings but in the meantime I'm using an old 500MHz Pentium II running Windows98. This consumes about 45W normally but by turning off the hard drive this reduces to more respectable 21W. The shortest delay to turn off  the hard drive is 3 minuits, I'm making measurements at 15 minuite intervals, so the average is about 26W. I plan to try logging to a USB memory stick so the hard drive will never need to run.
If any one is interested in setting up their own data logger I'm happy to talk you through what I've done, contact me at m.fendall@xtra.co.nz.

Post script 10/5/10
Running the logging software and logging to a USB drive does not prevent the hard disk from starting as I had hoped. If anyone out there has an old laptop, even one with a stuffed battery, screen or keyboard, I would be pleased to put it into service as a data logger.
Cheers Mark