My Online Diary

Tuesday, August 25, 2009

Energy Use I Am Directly Responsible For

Phil Scadden, a Dunedin based scientist, recently wrote "Sustainable Energy - without all the hot air: a New Zealand Perspective" using data from the Ministry of Economic Development, Energy Efficiency and Conservation Authority and the Electricity Commission. More: and

The report includes this chart:

Energy Use You Are Directly Responsible For

So Stuff, Cars and Planes makes up 70% of energy use I am personally able to do something about. I need to be thinking more about "Stuff".

1. Stuff 39% - We try not to buy much stuff, and when we do we try to buy second hand. TradeMe is great for that. We try to limit our purchases to the Wellington region.
2. Cars 25% - We sold our Toyota 1400 back in 2004. Since then we've managed to car share, hire, do without, use public transport, taxis and cycle.
3. Planes 15% - We're trying not to fly. We haven't been on a long haul flight since 2005.
4. Food 12% - Since Adam was born in Oct 2007 either Michelle or I have been at home every day of the week. So we're doing a lot more hm cooking. I'm not what the energy implications of that are. I don't think we've done anything to reduce our food related energy budget.
5. Home energy 9% - Most of this blog has been about my home energy projects - which has been fun.

Wednesday, May 27, 2009


I'm now working on installing pelmet above all the curtains. Pelmets help stop/reduce hot air being "sucked" behind the curtains as the cold air next to the glass falls to the floor. It also helps that our curtains drop all the way to the floor.

This is my first version - unpainted at this stage. That's the cheap heat pump I installed back in 2004 - still chugging along, keeping us warm. It's not as quiet as newer/fancy ones - but it does keep us warm.

More detail on my pelmet construction here.

Cheers, Paul

Tuesday, March 25, 2008

Interim HERS assessment

Here's the interim certificate (2 meg), - this is interim until EECA get all of the star rating bands confirmed and the room heating star calculator confirmed, as soon as these become available updated certificates will be issued.

Friday, February 22, 2008

HERS assessment: 6.5 stars

My house has a 6.5 star HERS rating.

The Home Energy Rating Scheme is a new programme the government has started (this month) to provide standards based home energy audits. The assessments are carried out by nationally credited assessors.

My assessment was done by Steve is from Ecosphere. He spent 30 minutes measuring the house dimensions, walls, foot print and windows and documenting the insulation, space heating and hot water heating we've got. Then a few hours back at the office feeding the data into the special HERS software, plus some more to write up a list of improvement recommendations.

He says; "your house has a 6.5 star rating [out of 10] which is exceptional considering the age of your house. That second layer of insulation in your ceiling was worth half a star."

"...the only realistic recommendations that could be made for your house were, new sealed double glazed windows (which would save you approximately $50 a year in heating costs), and replacing your heatpump with a highly efficient 6 star rated unit, which if used in conjunction with a low voltage heat transfer system would be able to save you more."

It's nice to have external validation for what I've done. The windows were my main (low priority) insulation project going forward - so it looks like I'm on the right track.

It would be nice to get it up to 7 stars.

Here's the interim HERS report for my house.

Thursday, December 20, 2007

End of year update

It looks like our energy usage will end up about 5400 Units, which is more than the 5000 Units of the last two years. Bummer.

The first half of the year went really well. We were tracking at or below all other years. But then on the 3rd of October, on a dark and stormy night, we had a baby at home. We ran the heat-pump almost 24 hrs a day for about a week. And, of course, we started washing nappies almost every day. That made October almost as power hungry a month as mid winter June/July.

Once again - it's really hard to tell what effect my insulation efforts have had. There's no blindingly obvious reduction in power. But... we're now a family of three and still we're going to be well under the 8000 Units that the government uses to define a "low user" of electricity. That's not bad considering all our home energy usage is electric - we don't use gas or wood. (Even the lawns are mown with an electric mower.)

We finally switched to Meridian last month. Once we'd transitioned from pre-pay to standard billing with Genesis, it was easy to switch providers - just a phone call did the trick. So now all our home energy usage is electricity generated form "renewable" sources (mostly hydro).

Last weekend I finished putting two 1000 litre rain tanks in behind the garage. The tanks cost $85 each from Pacific Wallcoverings in Porirua. On Tuesday a southerly came through and gave me 500 litres of rainwater. I'll be using this water for the garden over summer.

My next plan is to add another two 1000 litre tanks behind the garage and work out some way to use the water for the toilet and clothes washer. I haven't thought about greywater yet.

Well... actually, I have... and I can't think of a clever/cheap way to do it. It may be one of those tasks that is best left to experts.

Monday, October 8, 2007

Upgraded washing machine

I've just replaced our old cheap washing machine with a 2001 Indesit WD 11 front loading washer dryer. This should save some power and water.

But... Michelle and I have just had a baby - which will raise our energy usage a lot.

Sunday, September 2, 2007

Spring update

We're starting to get some good solar hot water now. Today we got the hot water cylinder up to 55 degrees C.

The solar PV is going very strong now as the day get longer. The charge hasn't been below 97% for weeks. The PV system is currently driving the weather station and it's data logging laptop. Over summer I might be able to switch to running the web server. I'm just a little worried my 4 Trojan T104 batteries are not enough for that load. Ideally I should add another 4 to give the PV system enough storage to last a few days of grey weather.

My purchase/wish list now is:
  1. Add 2 or 4 more Trojan T104's
  2. Add another 80 Watt PV panel (to bring the total to 4 panels)
  3. Upgrade to a 24 volt input true sine wave 1000 Watt output inverter
Step 3 means I can reconfigure the PV panel wiring to 24 volts (2 strings of 2 panels) - which will reduce the DC voltage lose over the wires.

Then I'll be ready to power the web server from solar panels all year round.

The plastic double glazing is now starting to show it's weak points:
  • if you tape the plastic out to the edge of the window frame it looks better, but in heavy winds the plastic edges start to "wheeze". They make a sound like a lamb bleating 100m away. Not entirely unpleasant - mostly odd.
  • if the window frame has any cracks in the joints - it will let in moist air. The moisture builds up and does not escape. I've got this on a sash window that I plan to restore this coming summer. I don't have this problem on the sash windows I've already restored.
The LED spotlight is working so well I jumped online to order some more. My main source was out of stock so I hunted around and found a Chinese source for 8Watt (equivalent to about 100Watts) warm white LED spotlights, for only US$30 each (plus shipping). I got 2. They are less bright than the first ones - but have a "warmer" light (ie yellower). They seem to be working fine too.

I may buy another of the previous type when they are available. Then I'll use the warm white ones out front, and the stronger cool whites on the garage overlooking the back yard and garden.

One more thing - my power company Genesis, raised our prices last month, almost doubling the line charge. Plus Genesis generates a fair bit of it's power from non-renewable sources (eg coal power stations) - so we'll switch to Meridian soon.

Cheers, Paul
paul at kennett dot co dot nz