My Low Carbon LifeBy - Article published in Home Energy : 2007 (reproduced with permission of Taylor Made Publishing Limited)
Posted on 24 April, 2007
Eric Hawkins explains how he went about integrating renewable technology into an existing typical British built house designed where possible not to waste energy or water.
In June 1999 Jane and Eric moved out of a rented bungalow to a new development on the outskirts of Wimborne, Dorset.
The key importance for Eric and Jane was that it was a brand new mid terraced 2 story house which faced as near due south as possible for an 'off the shelf' British built house, (found after months of searching).
Being the second of the new show houses for sale, we tried hard to stop the developer fitting a standard central heating system with radiators fitted under window sills and in places which reduced the overall space in all rooms, what we wanted was to install our under floor heating system, in order to start the process after taking possession of the house and agreeing to the price.
We did however manage to stop them tiling the bathroom which was the first thing we ripped out, having owned a luxury bathroom business before entering into the renewable energy industry in 1993.
My first task was the installation of a rain water harvesting system, but that did not start well as I found to my horror that no rain water down pipe was within my small back garden.
Straight away I contacted the developer and demanded a gutter down pipe to collect rain water off my part of the roof, which before was flowing into both my next door neighbours’ water butts.
While Jane, on the day of receiving the keys, started to work on the internal furnishings of the house, I set about sizing up a rear garden shed to take 500
Once the shed was installed, solar panels were fixed to the roof, and connected to the battery bank to convert 12 volts into 240 volts AC.
The new solar power supply will power the water butt pump and the main pressure pump, which transferred the filtered rain water back up to the loft space where a second water tank was installed above the existing one, which had to be re-located in another part of the loft space.
During the summer time, when rain water is less and more sunlight per day creates more power, it's used to power our deep freeze, so at all times we maximise the use of tax free electricity
Having planted out 5 fruit trees on the east side and flowering shrubs on the west side, gravel were laid on the remainder of the ground as we have 2 dogs. I moved to the front of the house where a second water butt was placed and connected to the front down pipe in order to collect rain water off the front of the house, and through a submersible pump, transferred this to the rear main water tank.
I then moved into the house to plan the real big stuff that of re-designing all the plumbing and hot water system without having to pull up the floor boards (after having the carpets already laid).
The typical copper lagged vented hot water cylinder in an airing cupboard connected to un-lagged copper pipes is one of the biggest energy wasters, along with meters of copper pipe un-lagged under the floor boards also wasting energy.
This was taken out along with the central heating Y plan and replaced with one of my own company’s' Thermal Stores. Before this was done I laid polyurethane boards over the existing glass wool insulation ( as this type of insulation always needs replacing in 10 years which is why so much heat passes through all ceilings) followed by permanent TG chip board flooring. With the whole of the loft space now boarded out as a testing centre for all the technologies I wanted to evaluate over the next 5 years, the 300 litre Thermal Store was placed into position. Unlike a conventional vented or unvented hot water tank, a thermal store is a vented copper tank which was designed to provide heated water for the heating of the house, and hot water at mains pressure for baths and showers, all from a single water storage tank. This type of water storage tank allows the water inside to be heated by solar, heat pump, gas boiler, electric or immersion heater.
Having completed the re-plumbing of the boiler flow and return pipes to the thermal store and circulating pump, it was time to install the latest vacuum tube heat pipe collectors onto the roof; having also plumbed these directly into the thermal store as well, using not copper but flexible stainless steel insulated pipe, so any potential leaks were on the roof or connected to a valve on the thermal store.
Next to be installed was the, unknown at the time, air to water heat pump,
Once we’d completed the energy efficient hot water and heating system, lagged all pipes that were visible, re-designed the bathroom and plumbed the new one using modern Pex al Pex pipe, I then looked at the water and energy waste between the time the hot water side of the kitchen sink tap was turned on, to the point of arrival, which lost 10 litres every time hot water was wanted. To solve this huge waste of water and energy; due to the uncontrolled way plumbers are allowed to lay un-insulated copper pipes under floors at minimum cost for the delivery of hot water to the kitchen sink, an under sink 10 litre heater was placed inside the kitchen sink cupboard connected to the cold water mains and from the thermal store.
As a Chef for 12 years prior to entering into the plumbing and building industry, what I wanted when hot water was needed to wash my hands after preparing food was hot water on demand, this was now possible.
By the time the 10 litres is used up (a sink full) the hot water from the thermal store has arrived
The last major job to be completed was the installation of the micro wind turbine and 6 x 70 watt solar panels to provide a hybrid wind solar 24 volt power generating stand alone system.
The 600 amp battery storage along with a 2.5kW inverter were also located inside the loft in order to power the circulating pumps and provide an emergency power back up in case of power cuts, not seen for many years, but will return as the UK starts to depend in years to come on more imported gas and oil.
The last part of living within the technology is making sure all the appliances using electrical power use the minimum amount, this covers the use of low energy light bulbs and ensuring all appliances are A or AA rated.
Over the past 7 years, installing all the equipment with thermal store, solar collectors and heat pump, all replaced over that time to keep up with the technology and design changes which came from the learning of the first purchased components.
Modern 7 day programmers, time clocks, radiator thermostats and cylinder thermostats are all part of being fully in control of what’s running, what’s burning up power, and energy when not required.
How to live within this Low Carbon Life
The original wall mounted gas boiler is programmed during the winter months to come on at 7.30am in the morning and switch off by 8.15am running at 50% of capacity to keep gas use to a minimum along with reduced servicing of the boiler to extend its life.
The gas boiler along with the solar and heat pump which heats the water in the 250 litre thermal store, which in turn circulates this water through the radiators as well through the plate heat exchangers which provide the hot water on demand at mains pressure for showers and baths.
Along the hall is a Honeywell CM67 room temperature thermostat which allows the temperature throughout to be set at different times of the day, 7 days a week.
My home has the heating programmed to run from 7.30 am in the morning to 10pm, 7 days a week, this does not mean the system pump circulates the heated water round the radiators 16.5 hrs a day. During the week my wife and I are at the office, leaving our two dogs to enjoy the 19c temperature we have set in the hall programmer between 10am to 4.30 pm. By the time we rise in the morning at 8am, we want a 21c temperature and the hot water on demand for morning showers. In the evening the programmer tells the thermal store the house requires reaching 22c and staying at that until 9pm, by 11pm we are in bed and the house temperature is lowered to 15c.
At 9am the heat pump is timed to come on and stays on until 9pm to maintain the thermal stores temperature which is programmed through the heat pump programmer to stop at 53c. Once the homes temperature has been reached, the circulating pump stops running and comes back on again when heat is called for again. All the rooms in the house not used are controlled by radiator thermostats set at 18c.
An air to water ducted heat pump located in the loft area draws in the rising heat from the rooms below and through the air vents in the roof space to produce an air temperature of 10-12c which delivers a hot water temperature of 45-50c over time, unlike a gas boiler which burns 16-20kW an hr against 1.3kW, delivering 3kW of heated water.
To reduce the daily low running cost of the heat pump, the 44 tube solar collectors during blue sky freezing winter days pump in higher temperatures faster than the heat pump produces, this helps to reduce the heating load cost during the day as this energy is 100% free and emits no carbon.
Solar water heating systems, when installed as we have, as part of a mixed range of hot water producing technologies reduces overall heat and hot water costs of a home by around 60% over the year.
During the months of September to April, 90% of the homes hot and cold water needs are met from rain water, filtered and pumped up to the two storage tanks in the loft from the large rain water tank at the rear of the garden.
This water is pressurised by a 3 bar auto boaster pump which is used for all toilets in the house, with the same water heated via the thermal store heat exchangers to deliver the hot water throughout the house. The only tap not supplied with filtered rain water is the kitchen drinking water tap.
Having a shower in the morning during the summer months, where 100% of the hot water is heated by the solar vacuum tube heat pipe collectors, which comes from rain fall is a wonderful feeling, because both are free, tax free and making a return on the original investment. Meanwhile millions of home owners continue, and will forever continue, to pay up every month through a direct debit, along with the tax added and increased prices for ever and forever.
The most expensive and longest pay back technology is micro wind, and the PV panels, which convert light, and whatever wind power can be gained from a roof top turbine.
For me it was about doing the whole thing, but maintaining my own power back up supply, not as the industry wants, for all solar and wind systems to be grid connected.
The problem with this, when the power does go down, no grid system works, either where I have designed my system to run my gas, hot water supply, and solar pumps, along with the lighting and fridge in the house, with the freezer in the shed switched over to the rear solar power system.
(You might think Eric is an eco hero, he is, but he is just like many of us who love our jobs; he is taking his work home. Eric is the Technical Director of
Solar Shed
Once the shed was installed, solar panels were fixed to the roof then moving into the shed to connect the solar controller’s inverter to the battery bank to convert 12 volts into 240 volts AC
The new solar power supply was to power the water butt pump and the main pressure pump which transferred the filtered rain water back up to the loft space where a second water tank was installed above the existing one, which had to be re-located in another part of the loft space.
Air Pumps
Unlike the ground source heat pump or air source heat pump which is located outside the building, this type of heat pump was designed for internal building use, for homes located in the loft space and for commercial applications any area where waste heat is lost or disposed of using some cooling system.
Eric's roof is used to collect wind, rain & Sun (both electric and heat). So whatever the weather his roof is working to save energy.