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Design, Convert and Build Work
In preparation for the building work we researched and set up an environmental preference schedule to help make conscious decisions in terms of sustainable selection of materials.
From a Design perspective we worked to knit together the existing physical charm and integrity of the buildings together with our needs and the energetic and environmental impacts to produce a practical and sensitive outcome.
During the Groundworks we reused as much hardcore and concrete as possible, crushing on site and minimised use of PVC in drains using almost entirely clay pipes; Chlorine from PVC being one of the worst greenhouse gases. With the wall construction we re-used bricks from a local demolishment rather than using new and used lime mortar in the new build. The internal blocks used included a high proportion of recycled aggregate. In theEcoCafe, half of the walls are traditionally lime plastered.
Regards Heating and cooling, we used relatively high levels of insulation to achieve the following target U values: Roof 0.15W/m2, Walls 0.25W/m2 and floor 0.20W/m2, which are better than current building regulations.
After considerable discussion and compromise we reluctantly ended up using for practical and cost reasons 150mm of Kingspan seconds in the roof and more happily 140mm of woodfibre bats on the south walls.
Underfloor heating was installed in the EcoCafe to be heated by a Talbotts biomass boiler fed by chopped willow from short term rotation willow coppice grown on the farm.
We kept a reasonable thermal mass within the building by putting some of the insulation on the outside of the original barn. Thermal mass is required to reducing temperature fluctuations though the day that can happen in a building that is internally insulated. This together with night ventilation, which consists of low level vents on the North side and opening roof lights to create a chimney effect which can be opened when temperatures are cooler at night, will aid temperature control and cooling. We included wind lobbies on both main entrances to minimise heat loss from drafts and air changes maximisinge internal comfort.
The Timber was all sourced from FSC or managed forests and some, for instance the Douglas Fir ceiling is English grown. FSC stands for Forest Stewardship Council which is one of the main accreditation bodies that ensure that wood has come from a sustainable source. See www.fsc.org. The floors in the EcoCafe and WholeHealth were cut from reclaimed beams – the oak we were told from some old log cabins!Timber requiring treatment was treated with Borax based material rather than more conventional treatments as it is considered the least harmful.
With the Decoration we principally used Auro paints as they have some of the highest environmental credentials available. They are now available for sale within the EcoCafé where we are pleased to be their regional agents.
Finally, the lighting utilises principally low energy bulbs with minimal use of halogen bulbs, and maximum use of natural lighting wherever possible with roof windows and light tubes in the toilets.
Next Page >> Environmental Preference Schedule Of Construction Elements
Designers and Engineers | Builders and Contractors | Specialist Suppliers
Environmental Preference Schedule Of Construction Elements, page 1
Criteria for selection:
- Design for low energy use (superinsulation etc)
- Minimising new resources (seconds/reclaimed etc)
- Using whole unprocessed materials first (solid timber, natural materials)
- Using low embodied energy materials (locally sourced, unprocessed etc)
- Using materials for a healthy environment (organic paints, no formaldehyde glues etc)
Preferences grades:
- ultimate aim
- good practice
- acceptable solution
- to be avoided
U values to be achieved including all openings bridging etc:
| Roofs | 0.15 W/m2K |
| Walls | 0.25 W/m2K |
| Floors | 0.20 W/m2K |
| Windows/glazed doors | 1.5 W/m2K |
The works carried out in the refurbishment and new construction at The Fold can be broken down into 27 categories and we have assessed each of these to illustrate the environmental decision-making process that affected all parts of the project. Firstly the specific treatment or material that we consider qualifies for each of the grades is identified for each category. The choice of material or treatment we made at The Fold is then presented and the reasons behind that choice are then explained.
A summary of the categories, the grading and choices made in The Fold is provided in tabular format at the end.
Builders Waste
- no export at all from site
- sorted into recyclable rubble/timber/metals etc
- burn waste
- indiscriminate use of skips
Choice: 2. Most of our waste material was eventually sorted but not without some confrontation.
Reason: The building trade are used to having skips to throw all their waste into without consideration and getting builders to sort the waste required the development of a new mind set.
Foundations
- Local stone foundations with land drains around perimeter. Reduce thermal bridging to a minimum
- Reused brick or block with recycled aggregate on minimal strip footing
- new conc. block or new bricks on strip footing
- Trench fill or reinforced slab/raft foundation with new aggregate.
Choice: 4. Trench footing
Reason: The considerable additional cost of labour and material in a strip footing.
DRAINAGE
- earthenware
- spun concrete
- -
- UPVC
Choice: 1. Principally earthenware drain pipes with PU manholes. Also PU pipe on a long 150mm run for surface water.
Reason: Best choice and whilst more expensive than UPVC still affordable.
Next >> Environmental Preference Schedule Of Construction Elements, page 2
Designers and Engineers | Builders and Contractors | Specialist Suppliers
Environmental Preference Schedule Of Construction Elements, page 2
ROOF INSULATION
- cellulose, sheep's wool or hemp/cotton with thermal broken timber I beams
- reused insulation boards
- mineral wool and expanded polystyrene
- PUR, foam insulation, extruded polystyrene
Choice: 4. 150mm Kingspan 2nds (PU foam)
Reason: Price and practicality - lack of experience with I beams and construction concerns with a thicker roof, which would have been 300mm, if our preferred choice of cellulose had been used.
FLOOR INSULATION
- Mineral wool,(glass wool & rockwool) Expanded polystyrene
- Foamed glass
- Perlite
- Extruded polystyrene PUR
Choice: 4. 90mm extruded PU foam.
Reason: We had planned to use expanded polystyrene but problems with floor levels left us with the choice of major amounts of underpinning or saving hight with the more efficient PU.
WALL INSULATION
- cellulose, cork, wood fibre boards or hemp/recycled cotton
- Mineral wool or EPS
- Foamed glass
- PUR, extruded polystyrene
Preferable to insulate outside existing structure and clad
Choice: 1,2 & 4. Granary south facing walls; 140mm Pavatherm wood fibre boards
Outside east & north sides; Kingspan seconds. New build; 100mm of mineral wool
Reason: Practicalities with Pavatherm proved quite testing and expensive. Though this experience would help with another project. In places space was very tight and this also influenced choice.
WALLS (new) External
- Cob or earth, durable wood
- reused brick or stone
- new brick or concrete blocks made with recycled aggregate
- concrete blocks, aerated autoclaved concrete blocks, strong cement mortars, tropical wood, preserved wood
Choice: 1 & 2. Reclaimed brick outer skin and Stranlite concrete blocks inner skin which are made with selected aggregates including graded bottom furnace ash and pulverised fuel ash.
Reason: Principally the aesthetics of remaining in keeping with the associated buildings which the planners were keen on but also cost and experience with alternatives. We experimented with construction of the new lobby to WholeHealth using a timber frame with hemp lime in fill panels finished with lime and would like to try a Cob or straw bale construction next.
WALLS (new) Internal
- Timber frame, clay block, cob or earth
- Sand lime blocks, flue-gas gypsum blocks
- Cellular Concrete blocks, natural gypsum blocks
- Concrete, strong cement mortars
Choice: 1 & 4. We had chosen to use some new clay blocks from NTB but unfortunately they failed building control tests and we fell back to using concrete block and insulated timber frame with plasterboard.
Reason: Clay block where thermal mass required otherwise timber stud.
TIMBER FRAME EXTERNAL WALL FINISHES
- Rain screen of durable timber from sustainable source
- Lime sand render on lightweight lath
- Fibre/cement sheet rain screen
- hard cement render/new brickwork screen
Choice: 1. Feather edge English Larch boards single nailed onto timber frame
Reason: Ist choice, practical and affordable
INTERNAL WALL FINISHES
- Local timber finish or lime-washed earth walls
- Lime or clay plaster on masonry, timber lath or wood wool slab
- Gypsum (natural or flue gas derived) plasterboard and plaster skim
- MDF, plastic boards
Choice: 2 & 3. About half of the Granary was finished with lime plaster on either brick panels or woodfibre boards and half was plasterboard with gypsum skim.
Reason: Our builders had reservations about using lime plaster but we found a local lime plasterer who did a great job and put to rest any fears. We used lime from Mike Wye in Devon who offered great support.
Next >> Environmental Preference Schedule Of Construction Elements, page 3
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