Lee Fordham from Architype simplifies some of the terminology you might come across if you're thinking about doing a sustainable self build.
Interview with Lee Fordham
Shortly after qualifying as an architect in 2004, Lee spent time travelling and working for architecture practices in New Zealand and Australia. When he returned to the UK he decided to pursue his passion for sustainable design and started working at Architype, one of the UK's leading sustainable architects, where he is now an Associate Director.
A beginner's guide to terminology
For those that are just setting out in their self build journey there can be an overwhelming array of technical terminology used that can be baffling to anyone outside of the industry. Lee takes us through some of the common terms that you might come across in a sustainable self build.
Passivhaus / Passive House
Passivhaus (Passive House in the United States) is a building standard that was developed in Germany around 30 years ago. Using physics, the aim is to reduce the performance gap between how the building is designed to perform, and how it actually performs.
The aim is to make the building more comfortable for the occupants and reduce how much energy the building uses, which is done with a better quality of build.
The experts will use the Passivhaus Planning Package (which you'll hear referred to as PHPP), which essentially is a very complicated spreadsheet of data that allows them to design a building that will meet the Passivhaus criteria. The contractor will use that information to construct the building, and a certifier will guarantee the work and certify it if it meets the required standard.
You'll commonly hear a Mechanical Ventilation Heat Recovery system referred to as an MVHR. They're most likely to be used in Passivhaus buildings, but not exclusively. It is a ventilation system which extracts the used air from inside a building. It takes the heat from that air and mixes it with fresh air which is being brought into the building from outside, to provide every room with fresh, pre-warmed air.
The air is filtered coming into the building, and different filters can be used according to whatever is in the external air in that area.
A key benefit over natural ventilation is the element of control over any given space, ie removing moisture from bathrooms etc.
An MVHR for a domestic dwelling is roughly the size of a combi-boiler and will need to be incorporated into the building's design.
Foundations / Footings
These will usually be designed by a structural engineer and are what sit under the building to evenly transfer the weight of the building to the earth. The type you use might be dependent on what your ground conditions are like, but some examples are pile foundations, deep strip foundations and raft foundations.
A complicated one to explain, but essentially it's a way of measuring how thermally conductive a component or a series of components (like a piece of glass, wall or roof) is. It is the rate at which heat travels through. The lower the U-value, the better it is.
The aim is to have fairly consistent U-values across all the components in a building. Having just one element that isn't consistent could act as a magnet for moisture and potentially damage the structure. This can partly be achieved by better insulation, triple-glazed windows etc.
The U-values form part of the data that feeds into the PHPP system.
At a very basic level, this is about eliminating drafts in a building. It's relatively easy to achieve but needs to be thought about at the design stage. At Architype they denote the airtightness layer on their detailed drawings using a red line, which shows the contractors where to take particular care in the construction so as not to damage it.
To meet building regulations, when the building is finished an air test will be carried out. The building has a giant fan attached to it and is either positively pressured, ie blowing air in, or negatively pressured, ie extracting air. The rate at which the air leaks gives you your air test result. It is a measure in pascals of the pressure of an internal area. Building regs require you to get a result of 10 or less.
The method in a Passivhaus building is slightly different. This takes an average reading from the building being both positively and negatively pressured, to give an n50 value which is how many volumes of air changes there are in an hour. The Passivhaus requirement is that it should be less than 0.6, so significantly better than building regulations.
Build system / construction method
This is a way of describing what method you are going to use to construct your building. Examples include timber frame, masonry, brick and block, insulated concrete formwork (ICF), pre-cast concrete, in-situ concrete, and cross-laminated timber.
You can even go to the factories and choose your handles, paint finishes, floor finishes etc. When they reach the site they are connected together. The advantages of building the elements off-site is it can be quicker, they're not subject to delays or damage from the weather, and often it can result in better quality and working better when brought to site.
Lee says that this is a difficult one to explain as there are many different interpretations of what it means.
Generally it refers to off-setting the energy use in a building. So the better your building is, ie a Passivhaus, the less carbon you have to off-set because you're not using as much energy.
Looking deeper into it, some people will be referring to zero carbon in use, which is the energy that is used starting from the point of when it's been built, through to its end of life.
But there's also embodied or sequestered carbon, which takes into account everything to do with the design and construction of the building, together with the in-use energy and sometimes through to the demolition. This is more complicated to account for, although there are tools which can help explain for instance, how much energy is used in getting a tree from Germany to the UK to use in a timber frame.
Whereas self build has many decisions for you to make, whether or not you're doing it in the purest sense of building it yourself, or whether you're commissioning someone to carry that out for you, custom build can take some of those decisions away from you. There will be an offering from the custom build company, but with options for you to customise it. That could be in terms of the style of the house, the layout or the finishes. It might not be as individual as you would get with a self build, but it can take away a lot of the headaches!
Solar shading / brise soleil
Effectively the same thing, brise soleil or solar shading would be used on the south facing side of a building to limit the sun coming in during the summer months when you don't want the building to overheat, but allowing it to come in during the winter when the heat is required. Generally it would be a horizontal component that sits over the south facing glazing, whether that be a roof overhang, external canopy or series of louvres.
On an east or west elevation you would usually have a vertical component, and that's just to do with the angle of the sun at certain times of day and certain times of year. Windows on the east and west elevation can be harder for dealing with glare and overheating issues.
Lee says the ideal situation is to have the building facing south where the solar gains can be controlled more easily.
Renewables refers to technology that generates energy. This could be photovoltaics, wind turbines, hydro power etc.
Air source and ground source heat pumps
An air source heat pump takes energy from the temperature in the air. Any air above zero degrees has energy in it and this can be taken and transferred into heat or hot water for your house. Similar in size to a washing machine, they're put on the outside of a building.
The ground source heat pump works in much the same way but will take the energy from the ground. They have pipes which can either be spread horizontally in the ground which will require a lot of space, or as a vertical spread of pipes, which need less space but are a lot more expensive.
Plans, elevations, sections and details
These are examples of the different types of design drawings, created by Parsons and Whittley for Ben Adam-Smith's house:
Plan – This is an aerial view, looking down onto the building. You can have different plans to show each floor of the building, but they can show the roof, doors, walls and windows, together with the internal layout.
Elevation – An elevation is a drawing of what the outsides of the building look like from where you're standing. A south elevation for example would be the side of the building that is facing towards the south.
Section – This is like slicing down through a building to show what's inside. It will show the components of the walls, floors, roof etc.
Details – By taking a section drawing and zooming in you will create a detail. They can be various scales, such as 1:2 or 1:10, and are an in-depth analysis and instruction for the contractor showing how to construct that part of the building. It would show them where the airtightness line is, where the insulation is, and how wide cavities would need to be.
Soft landings and performance monitoring
A soft landing is about making sure that once the building has been constructed, that the operator of that building knows how to use it. Obviously if you've built it yourself then this wouldn't be necessary, but if you've largely commissioned other people to complete the project then you should have someone tell you how it all works.
Performance monitoring can take place throughout the build process but in particular Lee refers to monitoring once the building is complete. This uses sensors to check on things like the internal temperature, humidity and CO2 levels, to make sure the building is performing as it was designed to do.
The way you tender will depend on what kind of contract you will have, but essentially a tender is a set of information that is put out to someone for a response. They will price up the aspects on the tender and return it with their figure and requested documentation. It can be a tender for a design team or for a contractor. The returned tender documents are then scored and weighted according to whatever your priorities might be. For some that might be 80% of the marks will be based on how competitive the price is, but for others they might weight it more heavily in favour of quality and not necessarily who is the cheapest.
A key thing is to make sure the information and drawings you are sending out are as comprehensive as possible. That way it can be priced accurately for what you will be needing. Without that detail they will be adding an element of price risk to their response which will invariably make it much more expensive.
- Sill – The ledge at the bottom of the frame.
- Head – The top of a window where it meets the wall. It can be internal or external.
- Jamb – The side of the window
- Reveal – The part next to the jamb. Can be internal (usually plasterboard) or external (usually timber or brick). If the reveals are set very deep into the thickness of a wall they can provide some shading to the window
- Mullions and transoms – Found on traditional Victorian style windows, the mullions are the vertical bar in the middle of the window, and the transoms are the horizontal bar.
- Trusses – The pieces, usually made of wood, that actually make the roof structure
- Joists – A horizontal structural element that supports the floor and/or ceiling
- Eaves – The part of the roof that overhangs the wall. Usually if it's a sloping roof it would be the part which overhangs the gutter
- Soffits – Underneath the eaves, the soffits are the horizontal section that you can see
- Ridge – The point right at the top of the roof, usually where two pitches come together
- Verge – The part at the side of the house. Usually there would be a bargeboard or piece of wood that goes down the side
- Parapet – Usually a piece of wall that protrudes up above a flat roof
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