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Design Fixed Building

How It Works

How It Works

The design fixed building specification that has been input into the design section of the building control system for a particular dwelling will automatically populate the as constructed onsite and on line compliant documentation in the building control system.

The stakeholder but more importantly the builder uses their project ID for a particular dwelling to access the online as constructed documentation and download the customised onsite fixed building specification compliance documents for the registered dwelling. The builder downloads the customised pdf for the fixed building specification for a particular project by using the project ID.

The builder uses these customised onsite fixed building specifications to ensure the as constructed fixed building specification is equal to or better than the design fixed building specification, when the compliance or over compliance boxes are ticked, then this documentation can then be signed off and dated by the Builder. These on site checklists and technical data are needed to substantiating the performance of the fixed building specification need to be forwarded by the Builder to the administrator of the building control system.

It is important that the builder commissions all the fixed building specifications and provides instruction manuals for the promoter; the dwelling is not fully compliant until the fixed building specifications have been commissioned and instruction manuals provided for the promoter, the promoter should ensure that this section of compliance is completed.

When the administrator receives the onsite fixed building compliance documents and technical data, he informs all the stakeholders of the actual as constructed fixed building specification by editing the as constructed on line compliance documents, ticking the compliance boxes for the fixed building specification and recording an improvement if there is one.

The administrator informs the registered stakeholders that the online and onsite fabric compliance documents have been completed by sending an automatic e mail through the building control system. The stakeholders can check the fixed building specification on site or request the onsite compliance documentation and technical data from the builder/administrator.

7.0 Design Ventilation

Best Practice

7.0 Ventilation

Options

The calculator gives three options depending on the level of performance required

  • 1. If building to the 2005 and 2010 building regulations it is sufficient to use intermittent extract fans by either using trickle vents in windows or wall ventilation.
  • 2. If building to air tight levels of less than 6m3/m2/hr. 50 Pascal’s a continuous ventilation system may be required for occupant comfort, a positive input ventilation, or mechanical extract system should be considered, the Sap appendix Q system contains a searchable data base for these products. If using a mechanical Heat recovery Unit then an 80% MHRV with a fan speed of 1.5 W/l/s should be considered.
  • 3. If building to air tight levels of less than 3m3/m2/hr. 50 Pascal’s intermittent fans should not be used. At this level of air tightness a 90% mechanical Heat Recovery Unit with 1.0 W/l/s should be used, the SAP Appendix Q system contains a searchable data base of Heat recovery units.

Compliance

If the project requires a mechanical ventilation system, the builder needs to provide the Designer with the technical data proving the as constructed mechanical ventilation system is equal to or better than the design ventilation system, this technical data is required by the Designer to calculate the constructed DER. Advice on which system should be used can be found in an Energy Saving Trust document GPG 268- Energy Efficient Ventilation in Housing-a guide for specifies.

If a heat recovery system is used, the builder must have commissioned the ventilation system and prove that the promoter is in possession of the instruction manual showing how best to use the ventilation system for the tick boxes in the compliance documents for commissioning and instructions to be ticked.

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8.0 Design Lighting

Best Practice

8.0 Energy Efficent lighting

Options

The calculator gives three options, lighting will not really affect the efficiency of the building but it does add extra credits for the code of sustainable homes. Also it is important that the appliances used in the building are energy efficient and have a good rating.

  • 1. If building to the 2010 building regulations it is recommended to have 75% energy efficient lighting.
  • 2. If building to the Extreme Fabric Standard 100% energy efficient lighting is needed.

For all of the above scenarios the low energy lighting should have a luminous efficiency of at least 45 lumens/circuit watt internally and all the external lights to have at least 45 lumens/circuit watt which are automatically controlled by movement censors.

Compliance

Prove of compliance can only be a visual check by the Designer.

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9.1 Design Stoves

Best Practice

9.1 Stoves

It is advisable to eliminated open fires and if a secondary heating appliance is fitted that a closed room heater is used in conjunction with a sealed flue. An open fire can reduce the overall performance of a dwelling by up to 15% which needs to be compensated by other more expensive fixed building specifications to make the building compliant

Options

The calculator gives three options for flues.

  • 1. If building to the 2010 building regulations an open fire is not recommended, only use a room stove with a sealed flue.
  • 2. If building to the Extreme Fabric Standard a room stove with a sealed flue is the minimum requirement and the elimination of a sealed flue should also be considered.

Compliance

Prove of compliance can only be a visual check by the administrator/assessor onsite.

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9.2 Design Solar

Best Practice

9.2 Solar

Options

The calculator will design the area of the solar panels based on the occupancy of the dwelling, the assumption is also made that the panels are facing a southerly aspect.

Standard: 2010
Pitch of the roof :
Number of occupants :
Elevation :
Solar Panel :
Panel Area m² :

10.1 Design Hot Water Storage

Best Practice

10.1 Hot water Storage

Options

The calculator will design the capacity of the storage tank based on occupancy and if solar panels are being used. The design depth of the factory insulation on the tank is determined by the performance level chosen by the designer.

Standard: 2010
Storage :
Insulation Thickness:

10.2 Design Water Usage

Best Practice

10.2 Water Usage

Hot water demand can be reduced by decreasing usage, this can be achieved in two ways by reducing the capacity of baths and reduce the flow rates of the hot water taps to less than 120lts per day per person. The second way is to harvest rain water which improves the overall water efficiency of the dwelling, these water saving initiatives are rewarded by getting extra credits under the Code of Sustainable Homes when calculating the DER.

Options

The calculator gives three options for factory fitted insulation to hot water tanks.

  • 1 Water conservation is not required when building two the 2005 & 2010 building regulations.
  • 2 Reducing the capacity to 120lts per day per person gets rewarded in the Code of Sustainable Homes.
  • 3 Introducing a rain water harvesting system gets rewarded in the code of sustainable Homes.

Compliance

If water conversation is introduced, then builder needs to provide the administrator/assessor with the technical data proving the as constructed secondary system is equal to or better than the design system, this technical data is required by the administrator/assessor to calculate the constructed DER.

For full compliance the builder must have commissioned the rainwater harvester and prove that the promoter is in possession of the instruction manual showing how best to maintain the rainwater harvester.

Standard: NONE
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11.0 Design Boiler

Best Practice

11.0 Boiler

There are many different options when considering what boilers to use and they are included in the SEDBUK database, which ever boiler is chosen it is important that its design capacity is suitable for the project. With the options given in the calculator, the emphasis is on the fabric of the building so for this reason the boilers in the design information calculator are commonly used and are cost effective.

If the Designer wants to improve the minimum performance suggestions, their version of SAP will have different options that can be used and the Sap software can be used as a design tool.

If a building achieves a passive standard of 15Kw/m2/yr. for space heating the secondary heating system combined with a heat recovery system can actually become the primary source of space heating and domestic hot water, eliminating the need for a boiler.

Compliance

It is important that the builder provides the technical data to prove the efficiency claimed for the fixed boiler. This information should be based on the appropriate test standard as set out in the Guide and the test data should be certified by a notified body. It would be reasonable for Building Control Bodies (BCBs) to accept such data at face value. In the absence of such quality assured data, the BCB should satisfy itself that the claimed performance is justified

For full compliance the builder must have commissioned the boiler and prove that the promoter is in possession of the instruction manual showing how best to use the boiler.

Standard: NONE
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12.0 Design Heating Controls

Best Practice

1.0 Ground Floor

When considering which materials and typical details to use for the floor- the Designer should study the Construction Detail and technical data provided by this section of the system. The advice given is based on the "Fabric First" approach, technical data supplied and Foresites’ experience of designing and project managing energy efficient domestic buildings.

Which insulators and typical floor details are used for the full fill method

Insulators: There are two insulators used in the UK to insulate floors Expanded Polystyrene- Polyurethene/polyisoyarate. If building to the 2010 building regulations or better, Foresite recommend that the high density insulator Polyurethene/polyisoyarate with a better thermal conductivity is used.

Typical details: There are three typical details that can be used when constructing a floor slab: The insulation over the slab or under the slab, and a suspended timber floor slab. Foresite recommend that the suspended timber floor slab should be avoided, not because the U Value of the timber suspended floor but because this type of floor is hard to make air tight, for this reason the option is not provided in the design section of the system.

How to use the floor U Value calculator for the full fill method

The U value calculator will automatically provide the Designer with a recommended specification depending on the level of performance required. If the Designer wants to improve on this he can use the floor U value calculator for the full fill method of construction, when increasing the depth of the insulator in the calculator, the Designer should ensure the depth that is being input can technically be achieved.

The materials used in this floor calculator are suited to this method of construction, and Foresite are constantly introducing new materials to their calculators if the Designer believes that other materials should be introduced to the calculator please contact us on tech@foresitebuildingcontrol.co.uk

The integrity of the floor insulation for the full fill method

It is important that the floor insulation is installed correctly and that there are no gaps were sheets are butted together and at corners. It is important that a 50mm perimeter strip is used at all the exposed walls and that the strip has a minimum thermal conductivity of 0.025W/m2K. The cavity wall for full fill needs to be below the DPC level so it is important that the cavity insulation used will not absorb water and is breathable.

Compliance: As part of the Foresite building control system, it is important that the builder downloads the customised compliance documents from the as constructed section of the system. The building control system will automatically provide the builder with the floor slab onsite compliance document which will have every element of the design floor specification on it, the builder should only tick the integrity of the insulation box if the described specification is equalled or better by what has been actually used on site and if the quality of the workmanship is good. The integrity of the floor insulation should be checked by the other registered stakeholders involved in the project.

the Designer should use this compliance document as prove of compliance and should input what has be shown on this document when inputting the floor data into their version of SAP, if this document is not provided the Designer should use a default figure of when calculating a Floor U value.

The thermal bridge floor detail for the full fill method

It is important that the builder constructs the floor slab as per the floor detail provided by the building control system and if the builder is in any doubt as to what is required, if he goes to the as constructed section of the building control system he will get a detailed description of what is required from viewing online or downloading the onsite compliance document.

Compliance: As part of the Foresite building control system, it is important that the builder downloads the customised compliance documents from the as constructed section of the system. The building control system will automatically provide the builder with the floor slab onsite compliance document which will have every element of the design floor specification on it, the builder should only tick the y factor box if the detail shown has been completed as per the generic drawing shown and with good workmanship. The quality of the y factor floor detail should be checked by the other registered stakeholders involved in the project.

The air tight floor detail required for the full fill method

It is important that the as constructed air permeability is at least equal to the design air permeability, this can only be achieved by attention to detail by the builder at all the construction details in the building, so it is important that the builder follows all the air tight instructions for the floor provided by the onsite floor compliance document that can be viewed on line by the builder.

The builder needs to tape and seal around all the services that come through the ground floor slab and make sure that the services are in the correct position, if services need to be moved the DPM will damaged causing air leakage. The DPM or air barrier needs to be taken above the DPC and an air tight seal needs to be made between the DPM and the air barrier being used to the walls.

Compliance: Compliance can only be proven when an air test is carried out on the completed building, but it is important that the builder goes through the checklist at each junction, this will improve the chance of the complete building reaching the design air permeability.

Foresite are constantly adding new details and materials to this section of the system. assessors who are registered can contact us with details of new materials and details to tech@foresitebuildingcontrol.co.uk.

Standard: NONE
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