January 25, 2015What is Fabric First Construction?
What is Fabric first construction?
A ‘fabric first’ method of construction does exactly what it says on the tin: with priority being given to getting a dwellings fabric right, first and foremost it means to attain a well-built, air tight and energy efficient building.
The class leader in terms of producing an energy efficient building is the ‘Passivhaus’ standard, we won’t deal with ‘Passivhaus’ in this post simply because there is so much information to take in, we will however write a further blog post to shout about the merits of ‘Passivhaus’.
There are many other manufacturers and suppliers of ‘Eco’ or ‘Sustainable’ houses, most with tried and tested results, have a look online and do some research!
If you are in Aberdeen/Dundee and are considering building a sustainable house using a ‘fabric first’ method of construction you will want to look for an Architect/Technologist that is versed in this, not all are!
The following list highlights some of the benefits of fabric first construction
- No need for renewables
- Fit and forget approach
- Built for life with little or no on-going maintenance
- Reduced cost
- High standards of energy efficiency
- Quick build time
Possibly the most productive way to ensure maximum energy efficiency and control build costs is to move over to a fabric first approach. Energy efficiency is incorporated into the building envelope and removes the need to be dependent on expensive renewable technology ‘bolt-ons’, thus contributing to keeping costs down.
The fabric first approach relies on 3 critical elements
- Super-insulation( U values)
- Thermal bridging
We will briefly explain each element
This gives the low u values required for each element of the building, roof, floor, wall etc. in a nutshell a u value is a measure of heat loss in a buildings elements, as we have said such as a wall, floor or roof. It measures how well parts of a building transfer heat. This means that the higher the U value the worse the thermal performance of the building envelope. A low U value usually indicates high levels of insulation. So better insulation = lower u value
Again this is another critical element of fabric first construction, building ‘Air tight’ effectively seals all ‘leaks’ focusing on service penetrations, doors and windows, extractor fans etc.
Specific Construction methods are used to overcome this and a ‘toolbox talk’ from your Architect/Technologist will outline what specifically has to be done regarding this.
Building Airtight means having no unwanted draughts and providing excellent levels of thermal comfort, however there is still a need for ventilation within a building to provide fresh air for the inhabitants, this is normally supplied in the form of ducted mechanical ventilation often with a heat recovery unit incorporated into this.
What is a Thermal Bridge?
A Thermal bridge is a weak spot in the insulation surrounding a house. Thermal bridge occur whenever there is a break in the continuity, or a penetration of, the insulation. Examples of Thermal bridges include:
- Junctions between walls and floors, and walls and roofs
- Reveals around windows and doors
- Holes made by pipes and cables
- Studwork in timber frame walls (interrupting the insulation)
- Steel wall ties in masonry construction
In recent times many ingenious ways have been developed in order to reduce the effect of thermal bridging.
Your Architect/Technologist will be best placed to explain the techniques required in order to eliminate thermal bridges.
So in this article we have attempted to explain in simple terms why a ‘Fabric first’ approach to building will ensure the basics are there for a sustainable project,
That is not to say that renewable technology cannot play an important role, indeed if the right advice is given it will ensure that the total package will be very efficient.
What does the future hold for fabric first construction?
Well the bar is being raised higher with building regulations becoming more and more demanding in terms of energy efficiency, so gradually building methods and techniques are having to change in order to comply with these changes…not a bad thing!
If you are considering building a house contact us, as specialists in sustainable construction we will be delighted to be of assistance.