Some of you may be interested in the various technologies used in the build. How they work and what they do. Although I want to build a house that looks traditional, I am making use of a number of the latest techniques to incorporate modern living and reduce future energy consumption.
Although the ground in which my new home sits is almost perfect for building underground (free draining chalk – even after the wettest winter for 250 years the bottom of the excavations are bone dry), it is vital to ensure that underground living space is warm, dry and welcoming. this starts by constructing reinforced concrete floor and walls made of waterproof concrete.
Naturally concrete resists water but the gaps and pores allow water to penetrate. Concrete can be made waterproof by using a high cement / low water mix and adding chemicals to make it workable. Phil Sacre supplies a super-plasticiser which he adds when the mixer arrives on site. This chemical when mixed into the “dry mix” reduces its viscosity and allows it to be pumped and worked. The concrete must also be carefully poured and vibrated to ensure no gaps. Contact Phil (listed on my contractors page) if you want to know more.
The advantages of a timber frame are many – short build time, less labour, shorter time to weatherproof; but they have to be carefully engineered, manufactured and constructed. My timber frame design is based on 300mm thick wooden “I beams”. Touchwood homes specialise in this construction method and have many Passivhaus projects completed.
All of the walls floors and roof are constructed from these “I beams” and then the whole is surrounded by weatherproof racking board. The whole house can be up in about 5 weeks.
Cellulose is a better performing insulator than other insulation materials such as polystyrene or polyisocyanate, and many natural materials such as sheep’s wool. It is made by shredding waste paper and adding borate which introduces fire, animal and mold resistance. This technology is sequestering thousands of tonnes of carbon which would otherwise be released as methane gas at landfill. It is a very green and effective insulation material.
Once the timber frame is complete, the air-tightness membranes are in place and first fix electrical and plumbing are complete, a Warmcel contractor will visit and spray the cellulose fibres in between the wooden “I beams”. It will also be sprayed into the floor spaces and internal stud walls. This greatly improves the air tightness of the whole building and is a great sound deadening medium making the house quiet.
One of the biggest wastes of energy in a home is air that energy has been expended to heat escaping from the house. This happens because traditionally built houses have air gaps all over them resulting from the imprecise nature of the building method used. In addition windows are built with trickle vents to allow a certain amount of air flow though the house.
Key to reducing energy use in a low energy home is to stop heat being wasted by hot air escaping to the outside. Touchwood homes will build my timber frame to a very tight tolerance in their factory. Furthermore when the frame is erected membranes will be used to cover all the potential gaps in the frame to ensure it is “air tight”.
Although very low air loss can be achieved by these methods, total adherence to this route reduces my design options. I am not a slave to the lowest possible energy use. In my view appearance and design help to enhance the living environment/experience in the house. For these reasons – mainly associated with allowing light into the house (and making use of the great views to the north) – and introducing attractive design features, I have decided to accept a low but higher than achievable level of air permeability.
The heating requirement of my new home will be low, but I will need to top up the heat in the house. Biomass is a renewable source of heat and much cheaper than oil or gas for meeting the energy requirements. It is roughly equivalent to gas in terms of efficiency, yet it is renewable unlike gas.
The basement will hold a Solarfocus wood pellet boiler and a pellet store, supplied by Oxford Renewables – my son’s company.
External filling ports will allow a pellet delivery lorry to back up to the house and pump pellets directly into the store.
Solar thermal heating
To further reduce the pellets used by the biomass boiler, the sun’s radiation will be collected on the South facing roof and provide heat for the thermal store attached to the boiler. This will provide a background level of heating whenever the sun is shining. If more heating is required wood pellets will be burnt to bring water temperature in the thermal store up to the required temperature.
Triple glazed windows
Windows are probably the weak link in reducing the energy consumption of a new home. Especially if you (as I do) want a light an airy house with windows on the north elevation ( which in my case looks over farmland to the Goring gap).
Therefore it is important to choose windows with low air permeability and the lowest possible heat loss. i have chosen oak, triple glazed windows from The Green Building store. they look great and are very efficient. It is possible to get even more efficient windows but they will not fit so well with my traditional design. these offer a great compromise of form and function.
MVHR (Mechanical Ventilation and Heat Recovery)
I can almost hear you groan as you read through this and learn about the steps taken to stop air loss. Didn’t we all learn to sleep with the window open – it was good for you. “No one likes a stuffy house”.
To manage the air quality in the house and keep it feeling light and airy, an MVHR system will be built into the frame of the house by Touchwood when they build it in the factory.
The system is designed ahead of the build. For the purposes of the system design , rooms in the house are designated either “hot and wet” or “cold and dry”. For instance a kitchen or bathroom is “hot and wet”, a bedroom or lounge is “cold & dry”.
A network of ventilation pipes are run through the building with the following design. Air from “hot / wet” rooms is drawn out of them and pumped to the MVHR unit. At the MVHR unit the heat is extracted from the air so it is “stale, wet and cold”, then it is blown outside. Fresh clean air is sucked into the MVHR unit and directed over the heat exchanger where it is warmed with the heat recovered from the outgoing “wet” air. The warmed, fresh air is then delivered to the “cold and dry” rooms.
This systems recovers what would otherwise be waste heat and returns it to the house. At the same time it provides a flow of fresh air throughout the house.
We are now firmly in the world of the internet and connection of intelligent machines. Most convenient is the use of the cellular phone network and or WiFi. Both of these are subject to variation in signal strength and drop-outs especially inside a building with lots of steel beams, brick or stone. My new home shouldn’t be too bad for WiFi, once a good internet connection has been established. However to help with future as yet unknown applications and for transmission speeds, I have chosen to install a Cat 6 wired network throughout the house.
This works on a star arrangement. Wires laid throughout the house all come back to a central point. This is in the services area in the basement. The ADSL line is brought straight to that point and split immediately into voice and data. The voice signal goes to a special board which can provide the extension points throughout the house. Data goes to a network switch and can feed any of the 24 access points in the building. Some of those are dedicated for Wireless bridges so that the whole house can be reached with a wired or wireless internet connection.
A/V signal distribution
Audio visual signals are provided by the satellite dish, TV and DAB aerials fitted to the chimney on the East side of the house. Like the network wiring; the cables are taken directly to the services area and then distributed to aerial points throughout the house. The satellite cables are wired through a quatro multiswitch. Rather than taking several single LNB signals. the Satellite signal is split into four elements (H & V, + &-) which can be reconstructed at any outlet. This gives much greater flexibilty.
It is relatively easy to design and build all of these technologies into a home when designing it from scratch. It is extremely difficult to retrofit them to an existing home.
This is one of the reasons I have gone down the re-build route as well as the VAT saving !!