Showing posts with label kettle. Show all posts
Showing posts with label kettle. Show all posts

07 August 2014

Hand warmers and hot water bottle

When working from our home office I have committed to, wherever possible, warming myself rather than warming all the air around me.


The office is often the coldest room in the house and I have spent a lot of time there this winter. Besides wearing warm clothes (including ugg boots) and often wrapping myself in a blanket, I also started to put a hot water bottle under my feet at the desk. I am amazed at how successful this is at keeping me warm. One hot water bottle, wrapped in a towel, lasts a whole work day.


I also purchased hand warmers from our good friend Megan of Granny Funk Crochet.


Sometimes I will also warm a heat pack in the microwave and sit it in my lap for a while in the morning when it is most cold, or if I am working at night. With these aids, I virtually never turn a heater on for the office. I think better with cool air on my face, so these are both sustainability and productivity measures.

Initial Time: Boiling a full kettle for a hot water bottle takes about 5 minutes. Purchasing hand warmers involved some emails with Megan and a few days to wait for delivery.

Initial Cost: Extra hot water bottles purchased recently cost $12.95 each. They now have covers made out of cut up old jumpers, and I also wrap my office foot-warmer one in an old towel - no cost. Hand warmers were $30. Or you could sign up for one of the Granny Funk crochet classes and learn to make them yourself.

Ongoing time or cost commitment: Five minutes for the hot water bottle each time. A cost saving due to reducing the amount of energy used for heating (see below).

Impact: Boiling a full kettle of water (1.75L) when the temperature is 10°C uses approximately 661.5kJ of energy, or 0.184kWh ('units' in our system) - 184Wh, or about the same as leaving a 60 Watt light bulb on for three hours. (see my previous kettle post for the formulas). Microwaving a heat pack (wheat bag) uses around 42Wh to give warmth for about two hours.

When all attempts to warm myself with body heat, clothing and a hot water bottle fail, I use an electric oil-fin heater. This is a 1000W device, but as I would never run it flat out and it heats a confined space, the actual use is less than this. If I were to run it for nine hours of work day, it would use approximately 3.5kWh.

Using one boiled kettle instead of the oil fin heater for a day of warmth saves over 3kWh (units) a day, around 2.5kg of carbon dioxide every winter work day. 

Running the reverse cycle air-conditioner in our living area to warm enough house to reach the office is hard to measure, but the office is the far corner of the house from the aircon. A fairly conservative guess would be 5-6kWh per day to use the reverse cycle to heat the office, which is why we don't do that.