Energy Efficiency

Energy Efficiency


Energy efficient bungalowIn 1986, I visited the Milton Keynes Energy World exhibition, and I was very impressed with the energy savings that could be achieved with a carefully designed property.

So, therefore, I had a bungalow built that was safe and highly energy efficient.  I also wanted to avoid the potential hazards associated with timber frame properties, therefore the property is of conventional brick and block construction.

In December 1989 the new 230 sq metre bungalow that was custom designed for maximum energy efficiency and low running costs was completed.  Electricity rather than gas was chosen as it is safer, more reliable, does not have annual maintenance costs, and is therefore cheaper in the long run.

To minimise running costs, intelligent slim-line electric night storage heaters were installed. I used a computer model to compare the heat loss of the previous home to the new bungalow to determine where energy savings could be made using the right materials during construction. The end result was that a three-phase electricity supply was avoided, and only small storage heaters were needed in each room.

In 2019, with the availability of affordable and highly efficient air-airconcondsourced heat pumps, we removed the night storage heaters and installed a pair of highly energy-efficient air-sourced heat pumps that have resulted in significant running cost savings.

On the left is a 7.5kW condenser that drives three air-con outlets inside the bungalow; this system provides heating in the winter and cooling in the summer. 

The heat pumps are very efficient and use a maximum of 4kW to provide 12.5kW of heating or cooling.  In practice, they use between 500W to 2kW.

The effect of our energy conservation measures means (for our property and EVs) we have zero power usage between May to September and annual power costs under £900 at May 2023 electricity tariffs.


Energy Efficient Features

  • Polystyrene insulation under the concrete floor slab (this was not a building regulations requirement in 1989).
  • Thick carpets and underlay.
  • Engineering quality hard bricks to resist moisture absorption.
  • Thermalite high-performance trenchblocks for the foundations.
  • 130 mm insulating lightweight concrete blocks for the internal walls.
  • 75 mm wall cavity filled with mineral wool insulation.
  • Double-glazed hardwood stained windows with argon filling and low-e glass.
  • Fully draught proofed with no fireplace or chimney.
  • Mechanical ventilation and heat recovery system.
  • Air-sourced heat pumps provide up to 12.5kW of heating or cooling, but use a maximum of 4kW of power.
  • Foil backed plasterboard on the ceiling.
  • 300 mm of fibreglass loft insulation.
  • Primary rooms facing south, then east and west.
  • Few small windows facing north.
  • LED lighting, Wi-Fi controlled throughout.
  • Sophisticated computer-controlled system using X-10 modules supplied by Smarthome and X-10 Activehome and HomeSeer software.
  • Unobtrusive, sophisticated mains/battery burglar alarm system; though no details will be provided here.

Low Maintenance

Low maintenance was achieved by using:

  • Stained hardwood windows
  • White UPVC soffits, bargeboards, and architraves.


Since 2009 we made the following changes:

  • During October/November 2009, we replaced our CFL lights with 118 GU10 LED downlighters. These lights use between 1.8W and 3W each.
  • During November/December 2009, we replaced our 20-year-old mechanical ventilation and heat recovery system with a new sophisticated microprocessor controlled heat-pump based mechanical ventilation and heat recovery system. This new system is very sophisticated and can be easily programmed to suit our needs. It is showing significant energy savings while delivering increased comfort.
  • During 2012 we replaced the windows and doors with new high-performance hardwood windows with argon-filled low emissivity glass with a wider gap between the glass panes.
  • In 2013, we upgraded and extended our network infrastructure, replacing the original CAT5 cable with CAT6A cables and sockets rated for up to 10Gbs transmission.
  • Since 2016, all lighting in Redoak has been LED.
  • In 2018, we installed a pair of 10Gb 24-port network switches to provide 10Gb connections in all rooms.
  • In 2019, we installed a pair of air-sourced heat pumps to provide energy-efficient heating in winter and cooling in summer.
  • In 2020, we enabled Wi-Fi control over all our lights.
  • In 2021, we installed a pair of chargers for our battery electric vehicles using cheap off-peak electricity.
  • In 2022, we installed four extra solar panels and two Tesla Powerwalls to protect us from power cuts and to divert surplus daytime solar power to the batteries for use when we have insufficient solar power.  This saves us money and helps the National Grid by reducing our consumption of daytime power.
  • In 2022, we replaced our 33-year-old patio doors with high-efficiency triple-glazed, argon-filled fixed windows that match our existing doors and windows.
  • In 2023, we had an EPC performed on our property giving us a very high "B" rating, which is the highest in our post-code and in the top 0.1% in our council district.

Thanks and appreciation

I would like to express my thanks to the following companies who, over the years, have ensured the success of our projects:

  • Southern Electric Contracting Limited
    For advice and all kinds of help on energy efficiency and electrical control matters, and providing a skilled electrician who did the wiring of the computer-controlled X-10 system in 1990.
  • X-10 Europe
    Who supplied prototype X-10 evaluation units prior to their general availability, and gave me access to their developers for technical queries during my evaluation.
  • Butterley Bricks, part of Hanson Group
    Who offered helpful advice and told me to take whatever free samples I needed from their brick store. Because they were so helpful, they received the brick order.
  • Total Home Environment Ltd
    Who installed our new ventilation/heat recovery and heat pump system during December 2009. Please read about this project here.
  • Jasun Filters Ltd
    Who provide high quality and cheap filters for mechanical ventilation and heat recovery systems at a very good price.  They will even make them to the size you wish.
  • Axminster Carpet Company, Devon
    Who make great hard wearing carpets that are expensive, but worth every penny and which have worn well since 1989.
  • The Electrician
    Les, who took meticulous care over everything and who did an excellent job for us installing the original electric cabling in Redoak and also all the network and RF cabling.
  • R Hemsworth and Son, Gosport
    This company makes exceptional quality doors and windows to your specification at a fair price, and they have supplied all the doors and windows for our property. They offer a friendly and professional service.
  • SRS Facilities
    Whose engineers installed our air-sourced heat pumps.  Their engineers were very proficient and competent and performed an excellent installation service for us.
    Who provide the best range of Network Attached Storage (NAS) products, not just for commercial users, but for home users too.  Their NAS units come with a huge range of free software for security, multimedia and file storage. I've been buying them for years.
  • Octopus Energy
    The CEO of the company has instilled in their workforce that customer satisfaction is their number one priority. If you ever have problems, you will find that the customer services staff and engineers are first class, and they really do try to help you, and I like that.  Why not contact them for a quote and switch, and please use this link here to save us both £50.