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HTINews Article

Energy Efficient Home Design
by John Perry john@redoak.demon.co.uk

In 1986 I visted the Milton Keynes Energy World exhibition and I was very impressed with the energy savings that could be achieved with a carefully designed house.

So therefore, we endeavoured to have a bungalow built that was safe for the children and highly energy efficient. We also wanted to avoid the potential problems associated with timber frame properties so therefore our property is of conventional construction.

In December 1989 we moved into our new 230 sq metre bungalow that was custom designed for us for maximum energy efficiency and low running costs.

We selected electricity rather than gas as it is safer, avoids annual maintenance costs and is cheaper. To minimise running costs, we had intelligent electric night storage heaters installed.

The many energy efficiency features of our property are:

• Polystyrene insulation under the concrete floor slab.
• Thick carpets and underlay.
• Engineering quality hard bricks.
• Thermalite high performance trenchblocks for the foundations.
• 130mm insulating lightweight concrete blocks for the internal walls.
• 75mm wall cavity filled with mineral wool insulation.
• Double glazed hardwood stained windows with kappafloat glass.
• Fully draughtproofed with no fireplace or chimney.
• Mechanical ventilation and heat recovery system.
• Foil backed plasterboard on the ceiling.
• 200mm of fibreglass loft insulation.
• Primary rooms facing south, then east and west.
• Few small windows facing north.
• Fluorescent lighting throughout.
• Combined electric storage and convector heaters with each heater controlled by electronic sensors.
• Sophisticated microcomputer electrical control system now replaced with X-10 modules and Activehome software.
• Unobstrusive sophisticated mains/battery burglar alarm system; no details will be provided here.
  

Low maintenance was achieved through using:

• Stained hardwood windows.
• White UPVC soffits and bargeboards outside.
• White UPVC skirting boards, windowboards and alcatraves inside.

Home Automation using X-10 modules

• Our home is fitted with X-10 modules and the CM11A computer interface which is controlled by the X-10 Activehome software. This system enables central and automated control over all heaters, towel rails, lighting, appliances and the mechanical ventilation and heat recovery system. While the Activehome software controls the appliances most of the time, we have two RF Transceiver units that can override the units. The system comprises the following:

  CM11A Computer Interface
  This is currently connected to the Gateway P90. The CM11A controls all the X-10 modules. As the Gateway is switched off when not in use, only fast macros are used. When I buy a laptop computer, I will leave it switched on 24 hours a day connected to CM11A .
  
  Storage Heaters
  The ten storage heaters are in two groups, with each group of five heaters separately controlled by X-10 DIN appliance modules. The storage heaters all have individual electronic thermostats and receive a five hour boost between 23:30 and 7:30 (Southern Electric choice of time) and a two hour boost during the day. The day boost will be detected by an X-10 Powerflash, and depending on the temperature within our bungalow, the boost to either the hot water and/or the storage heaters may be prevented by the CM11A.
  

  Convector Heaters
  All storage heaters in rooms have combined convector heaters and each of these heaters is controlled by a separate X-10 Appliance Module. A macro in the CM11A is set to switch "All Convector Heaters Off" periodically during the day and night to avoid inadvertant use. The presence of the day boost to the storage heaters will be used to switch "All Convector Heaters Off" when the signal is received, and to keep them off for two hours after the day boost is complete.
  

  Towel Rails
  We have electric towel rails, one in each of the en-suite and bathroom. These towel rails are controlled by X-10 Appliance Modules to maximise comfort while minimising cost.
  

  External Lights
  We have three external fluorescent lights which are controlled using the "On at dusk" and "Off at dawn" feature of the CM11A. The CM11A allows a time offset to the dawn and dusk settings, which of course self adjust during the year.
  

  Mechanical Ventilation and Heat Recovery System
  This system extracts warm moist air from the bathrooms, kitchen and utility rooms which is used to heat fresh air drawn in from the outside that is then blown into all the other rooms of the bungalow. On-off times are controlled by an X-10 DIN Appliance Module at the optimum times to minimise cost and maximise comfort. This unit eliminates condensation and allows us to keep all windows sealed from autumn through to the late spring. Since the unit is situated in the attic, it is inaudible.
  

  Lighting Circuits
  Currently we have two X-10 DIN Appliance Modules that switch on and off two separate lighting ring mains. At the moment the fluorescent lights are not individually controlled, though this may change with them driven by X-10 motion detectors in the future. The X-10 Appliance Modules supplement the burglar alarm system by giving the bungalow a lived in appearance while we are on holiday by using the security mode feature of the CM11A.
  

  Other Appliances
  X-10 Appliance modules are used to control the washing machine, tumble dryer and dishwasher.
  

  Christmas
  Last and by no means least, at Christmas time, X-10 Lamp Modules control the on and off times and vary the brightness of the lights on the Christmas Tree and in our boys' bedrooms. Energy can be saved here as the lights need not be as bright when it is dark, as during the day.

  I would like to express my thanks to the following companies who have ensured the success of this project:

  • Southern Electric Contracting Limited
    For advice and all kinds of help on electrical control matters and providing a skilled electrician who did the wiring of the computer controlled X-10 system.
    
  • X-10 Europe and Travis Interactive Systems Limited
    Who supplied prototype X-10 evaluation units prior to their general availability, and gave me access to their developers during my evaluation for technical queries.
    
  • Butterley Bricks, part of Hanson Group
    Who offered helpful advice and told me to take whatever free samples I wanted from their brick store. Because they were helpful, they received the brick order.
    
  • Flebu Limited, Oxford
    Who provided the mechanical ventilation and heat recovery system and willing after sales service.
    
  • Axminster Carpet Company, Devon
    Who make great hardwearing carpets that are expensive, but worth every penny.
    
  • The Electrician
    Who took meticulous care over everything and did an excellent job for us. I can recommend a good electrician if you need one in Hampshire.