Saturday 6 April 2019

Annual Report after seven Years

Here is the annual report for the house after the first seven years.


It has now been seven years since we turned on the sustainable features of our new home in the Fjord block of Aotea, New Zealand

Changes to the system:
At the start of 2018 (January) we installed a further 12 solar panels and a 10kwhr LGC powerwall to the photo voltaic system giving a considerable boost to the solar capacity which is now capable of delivering a maximum 4.67kwp each hour. With the new system in place we can get through most months with just the solar power and powerwall backup at night.

In late 2017 we also increased the number of panel arrays on the DSHH system and the two new banks of water heating panels have the new panel version installed. This has increased the capacity and reduced the time for heating the system. The maximum core temperature is still about the same but during winter months there is now more capacity to keep the floor slab at the desired temperature without supplementing from the core.

We continue to be pleased that our fervour for sustainability has been vindicated with the results being very encouraging.

The System:
Over the seven years we have had numerous people who have visited to see and talk to us about the features that we have installed and to get a feel for how sustainability might help them in their own house planning. This has led to other houses in the region being constructed with similar features. While there is a lot of recognition of the value of sustainability especially in providing healthy living and wellbeing, the number of other homes in the region, which have picked up on the sustainability features, is still fairly small.

It is encouraging to see the growth in sustainable products over the years, the reduction in price, especially solar panels and the options for home owners has certainly increased. More building companies are now offering sustainable products as part of their build options.

The home was finished in December 2011 after going through the design and build process which included educating our design architect and builder on the sustainable technologies that are available. The house was designed and built by Hayward Homes Limited who as a result of the experience gained with our build now promote themselves as a “Sustainable Home” designer and builder for Wellington.

This report comments on how each of the key systems are functioning, the results and the costs and benefits.

The Key Features
The two key features in the house reported on below are:  
       Digital Self Heating Home system (Energy Efficient Homes Ltd), expanded in late 2017 with two further sets of panels.
       11 panel Photovoltaic system (Powersmart) expanded to 23 PV panels and a LGC 10kwhr Powerwall (Harrisons) in January 2018.

There is also an update on the other features being;
       uPVC windows and doors (Weathertight Windows and Doors Ltd)
       LED lighting throughout (Lighting Direct)
       Water collection and recycling systems (Watersmart)
       Polished concrete floors (Husqvarna system)


The Digital Self Heating System (DSHH).
The DSHH system provided by Energy Efficient Homes Ltd uses the sun in a solar water system to heat water. There are two arrays on our roof one of which provides our hot water heating for the house, the second providing the hot water for the thermal mass system.

The thermal mass system uses the solar system to heat water which then heats the ground below the floor slab. The heat is captured in the soil and a layer of core sand between the foundations of the house and below the floor slab producing 248 cubic metres of thermal mass as our core heat source. The foundations are deeper than normal to provide the thermal mass area, and hence the foundations are wider than normal giving the ability to increase the insulation on the outer walls. Two layers of 3.2 Batts insulation were used on all outer walls increasing the thermal seal of the house. The core is separated from the foundations and the floor slab by 30cm of polystyrene.

The core has steadily increased its thermal mass temperature as the ground under the house has been dried out and sits between 32 – 36 degrees C at the height of summer and it is this heat that is then put back into the floor slab during cold periods to keep the house in a range of 20 -23 degrees.

During the last few years we have realised that our main issue with the system is caused by the wind which comes from the north west and as we have a large bank in front of the house this acts as a ventura effect increasing the ability of the wind to rattle and lift the panels which over time impacts on the joints for the panels and loosens the connectors. With this in mind we have started a programme of tightening the connectors after spring each year.

During the summer of 2017/18 the core temperature reached 35C, and this dropped to 21C by the end of July as May and June were unusually cold months.

About 13% of annual power usage in a normal house is taken up in heating the home and with our system, and especially with the powerwall installed winter heating should be kept to a minimum for our house.

During the winter period we use supplementary electric heating to keep the internal temperature of the house around 20C and this is clearly noted in the power usage section of this report. The amount of supplementary heating has significantly decreased with the inclusion of the extra PV panels and the powerwall which supplements early evening heating.

Water heating is normally 33% of power requirements in a standard house and in our case this comes predominately from the sun, a significant power saving for the house. The solar panels heat our hot water for house use and this is stored in a 280 litre cylinder. The system has continued to work as expected during the year with no issues.


The Photovoltaic System
The photovoltaic system (Powersmart Ltd) was designed to provide a maximum of 2.09kw per hour, this was increased to 4.67kw per hour in January 2018 with the addition of 22 further panels Harrisons) and is connected through an inverter direct to Meridian Energy. Meridian receive any excess power generated during the day and while this power was credited in 2012 on a 1:1 basis up to 5kWhr per day this is now credited at just under 8c per unit.

In the last 12 months we have generated over 5.4MWhrs of power from the system of which we used just over 3.3MWhrs and distributed 2.1MWhrs to Meridian. After 7 years we have generated 22.5MWhrs of which we have used 12.6MWhrs and distributed 9.8MWhrs.

Over the last year we have been 80% sustainable – amount of power generated by the system compared with total power used. This is up from 40% in previous years.


The average KWhr provided by the power company (Meridian) during summer months is significantly different from the winter months. While this is expected given the electricity heating, you can also see that the winter average is coming down both for total power used and power from Meridian.

An average house is estimated by the power industry to use in excess of 10MWhr’s per annum. In our case in the last two years we have averaged 6.7MWhr’s per annum and in the 2018 year 80% of this power was generated through the PV system.

In 2012 the power cost was 23.19c per unit and in 2018 it is 29.95c per unit an increase of 29% over the seven years. During the 2017 year we saved about $1475 in power costs compared with an average house and in 2018 this went up to a saving of $2260. (see payback section at end of this report).

Other Features Updated:

LED Lighting
The house is fully lit by LED and after seven years we have had no light failures. There are significant advantages to LED. They run cold and hence can be fully covered in the ceiling by insulation, maximising the thermal seal of the house, they run at about one sixth of the power compared with other light systems and they have very long life. We had a very strong relationship with Lighting Direct who provided a very sharp price for the LED lights and fittings throughout the house.

If we had installed halogen we would have had the equivalent of 5.6kW of lights compared with the 800W of LED light that we have installed. That is a significant reduction in running cost for LED given that lighting is normally 12% of power usage. The LED’s are specified to run for 50,000 hours. I’ve worked that out to mean that we will not replace any lights in our life time even if we live to a hundred. The lights have been great with no failures and no issues.

uPVC Windows and Doors.
Our windows and doors are double glazed uPVC. Our uPVC system is a Belgium design specifically for the southern hemisphere, and came to us via Australia and was installed by a Dunedin company Weathertight Windows and Doors Ltd for the same price as aluminium.

The only door that wasn’t uPVC was the front door. This door was a standard wooden door, however due to thermal leaks around the door experienced in winter and during southerlies, this door was replaced during the second year with a uPVC door. The change in thermal seal is amazing and heat loss that occurred during the winter of 2013 has not occurred since.

uPVC has the best environmental rating of all systems with double the star rating compared with aluminium. The biggest advantage is no condensation and no heat loss using uPVC.

This year we had the windows maintained by Weathertight Window and Doors Ltd as some window handles were starting to seize up. The only other issue we have had is with the door handles where there has been discolouring of the key plastic panel and some chipping off the bottom of the outside handles. Otherwise all windows and doors are working well.

Water Collection and Reticulation
Our water collection and reticulation systems are both from Watersmart NZ Ltd. The system consists of a 5000 litre tank, buried in our front lawn which collects rain water off the roof. This water is used for the toilets and for all outdoor taps. It means that during dry periods we have plenty of water for the garden, however with a ban on, it didn’t seem proper to utilise the water we collect.

We also have a grey water irrigation system which collects water from the two bathroom showers, bath and basins and send this under pressure to our lawn and front garden area. This means that watering the lawn and garden is simplified, as it happened every time we have a shower.

During the last few years the pump in the 5000 litre tank had to be replaced and we upgraded to a more robust model. This summer the pump for the grey water system also failed and was replaced with a Bosch pump which should last considerably longer.

Concrete Polished Floors
All hard floor areas are polished concrete using the Husqvarna process. This includes the wet areas, (bathrooms, toilets and laundry) and the entrance hall and kitchen. We had some minor cracking in the concrete in the first year which appeared as part of the curing process. This was left for a year to ensure no other movement and all of the cracks have now been resealed and there have been no further problems and all of the floors have survived any earthquakes that occurred during the years with no problems.

Cost Benefit revisited.
I can compare the cost of the house with and without the sustainable and environmental features. When we started I thought the cost of sustainable features would be about 15% of the normal build costs, but I was surprised to find that the total additional cost for the features comes in at only 8.6% compared with a house without these features. I have used the additional cost between our system and what a normal house would have used in each calculation.

The two main systems are the Digital Self Heating Home and the Photo Voltaic systems, with most other features being secondary to those two systems. The payback period for the full system (not including the water systems) was originally estimated to be about 15 years at 2012 power prices. With the price of power continuing to increase the actual payback period for the original system is now about 11 years and reducing each year.

The additional panels and powerwall have a payback period of around 11 years as well.

We have not tried to put a value on the health and wellbeing benefits. Since we have been in the house the temperature has not gone below 17 degrees in any of the rooms and tends to stay around 20 degrees during most of winter. The humidity in the house is also lower than a standard house and these two factors alone make for a consistently warm, pleasant and enjoyable environment. It is a great house to come home to and the warmth on a cold winter’s day is still a joy to experience when you walk in the door.

The house has been assessed by a Real Estate agent and the sustainable features are considered to add considerable value to the underlying value of the property. All of the systems are guaranteed for greater than 20 years and should still be in good working condition in the later part of the century.

Our commitment to sustainability has been further reinforced and strengthened by our own experience and we would encourage anyone considering a sustainable home to take the plunge and enjoy the experience you will have.

Thursday 14 April 2016

Fourth Annual Report Now Available

Its hard to believe that it is now four years since we moved into the house.

Since that time the systems have slowly settled down with most working as intended, but as always there are teething problems with new technologies.

This latest annual report gives you and update on our systems and the performance. In theory we are one year away from being able to sustain our temperature requirements in the house for the full year, however reality is that we will still need some secondary supplementation during the colder winter months. It now appears that we should have at least two more sets of panels on the roof to achieve a balanced system summer ans winter. We only have room on the roof for one further array and we will get this installed in the coming months.

Enjoy the report.


Thursday 3 September 2015

Winter for 2015 Has Passed

Well another winter period has completed and as of 1 September we are heading into spring.

The three  months of winter have been the coldest months for many years with August being significantly wetter and colder than previous years.This is reflected in the lower than normal pv results for the period.
Likewise the core temperature plummeted as the system tried to keep the core to the 21 degrees it was set for.

The system has had a few frustrating issues of late with pressure being regularly lost in the solar water system. the pressure release system has coped with the events with no damage to the system but we are still endeavouring to find where the pressure is leaking from. This impacts on the ability to store heat in the core so hopefully will be resolved sooner rather than latter.

  




The core temperature fell to 20 degrees in July and has only just started to move back up. As we move into the fourth summer period for the system the expectation is that the core should get above 35 degrees by the end of this coming summer.



As indicated the level of power from the pv system in August is the lowest since the system was installed. Hopefully the long hot summer that is forecast will generate plenty of Kwhrs in the period ahead.

Thursday 2 April 2015

First Quarter 2015 Results

The first quarter of 2015 has produced a great January and February and slightly messy March but overall the results for the house and the systems are similar to previous years.

The core temperature peaked at the end of February at 32 degrees and has decreased slightly to 30 at the end of March. One assumes this means that the heat has spread into the core and has assisted in drying out the core so that it will be more receptive to heat gain in the future and the total cubic metre area has increased. Time will tell on that one.



 The photovoltaic system continues to produce steady and similar results from previous years.January is consistently the best month for pv output followed by February and then December. We are now up to just under 10MWhrs since turn on of the system.

January produced 385.7KWhrs which is the best month yet.


The third annual report has now been completed and is available on the site.

Thursday 4 December 2014

November Results 2014

Well its been two months since I updated the blog. The house continues to perform as expected and the core is once again building up temperature as we have had a fairly good spring with plenty of ultra violet light.

As you can see the core temperature is on the rise and has got to 27 degrees by the end of November. We are hoping that it will rise to about 34 -46 degrees by the end of the summer period and hence will nearly last right through the winter next year.



At the same time the amount of power being generated by the Photovoltaic system has had an excellent two months with both being significantly better than last year which was a poor year. 

During November there were 5 days with greater than 15kwhrs being generated compared with only 2 in October.
Roll on the rest of the summer.

Tuesday 9 September 2014

August 2014 Results

We are now at the end of the winter period and have slipped into spring.

During the last month we generated 196 kWhrs of power with a maximum of 9.95 kWhrs on any one day and a minimum of 2.14 kWhrs. QWe had three days with less than 2.5 kWhrs generated.

Overall the power generated for the month was slightly down on the previous years as can be seen by the graph.

The good news is that from now on we will see a rapid increase in power generated as we see increased daylight hours and better angle match with the arrays.

Next month we will be able to show the improvement in power usage for the house based on the increased core temperature mass and reduced need to back up during the winter months with electric heating.

 

Thursday 7 August 2014

July Results

Well here we are in the middle of the winter cycle and the worm has slowly turned with 135kwhrs of PV power being produced during the month which is slightly higher than in June.

The month was colder than last year with a concentrated spell of southerly winds keeping the temperature below 10 degrees for 15 days straight in the middle of the month.

There were no days where we generated more than 8 kwhrs and two below 1 kwhr for the day.

Roll on spring and summer.