ThermaSkirt used in 3,000m2 Office Project, combating cold front from floor to ceiling glass with the 4.5" Deco PR profile laid flat on its back across the large windows and patio doors.
This is a whole-house retrofit of Passivhaus standards in a radical, all-electric solution with the intention to reduce and eventually remove reliance on fossil fuels. Innovations include an experimental composite external render, intelligent electrically-heating windows and ThermaSkirt skirting board heating.
Passivhaus standards will be met using thermal mass, very low air permeability and mechanical ventilation with heat recovery, hopefully guaranteeing that the property will not require future retrofitting. The property will be extended and become larger during the Retrofit for the Future works.
Embodied energy is also considered in the proposals as well as operational energy, reflected in the choice of local suppliers and also in the choice of materials.
| Design strategies | |
| Planned occupancy | Predicted family of six to seven people. Children out to school on weekdays. Property currently void and tenants not confirmed. |
| Space heating strategy | Air source heat pump (ASHP) solution serving radiators with LTHW @55°C. Heat recovery from mechanical ventilation. |
| Water heating strategy | Hot water via integrated thermal store within indoor ASHP unit, linked to solar thermal panels & solar cylinder. |
| Fuel strategy | Ultra low all electric solution, offset by roof photovoltaic electricity generation. |
| Renewable energy strategy | High efficiency exhaust air source heat pump. Roof mounted photovoltaic electricity to be installed (0.3kWp). |
| Passive Solar strategy | High performance low solar transmission glazing. New extension increases space and opens up natural daylight. Radiators installed into skirting boards around each room allow flexible arrangement of furniture to ensure windows should not be blocked. Main living area and bedrooms above oriented almost directly to the South for passive solar heating. External insulation to boost thermal mass of the house. |
| Space cooling strategy | Cooling effect available from cross flow ventilation via MVHR system plus openable windows. |
| Daylighting strategy | Retain existing window sizes positions and replace existing solid door with window to allow light into new kitchen area, achieving a minimum average daylight factor of at least 2% and living room to achieve average daylight factor of at least 1.5%. |
| Ventilation strategy | High efficiency MVHR system linked to exhaust air heat pump system. Openable windows. |
| Airtightness strategy | Significant improvement, targetting Passivhaus standards. An 'Airtightness Champion' will coordinate between consultants and trade sub-contractors on site. Laps in membranes to be rigorously sealed. Gaps around window/door frames to be sealed. All windows and external doors to be draughtstripped. Holes around services passing through the external wall to be sealed.Holes around service pipes passing through suspended timber floors, around light fittings and pull cords in the ceiling to be sealed. Joints between the ceiling and the external wall to be sealed. Joints between drylining and skirting board to be sealed. Suspended floor air barrier to rear of property and new extension to be sealed direct to masonry wall. |
| Strategy for minimising thermal bridges | Returns in insulation to match reveals as part of continuous insulation. External insulation wraps the property. All major elements junctions considered. Doors in particular specified to reduce thermal bridging through frames and fittings. |
| Modelling strategy | Whole house dynamic modelling was undertaken in an iterative manner using ies ve software, SAP 2005 9.81 + SAP extension - see energy forecast below. ies ve software used with SAP interface (SAP2005 9.81 via JPA Designer vr 4.04b1 build 002). |
| Insulation strategy | Targeting Passivhaus standards, therefore considered use of external insulation to solid brick walls (to achieve U-value of 0.15 W/m2K); high performance windows (to achieve U-value of 0.81 W/m2K). Extensive upgrades also include new doors (to achieve U-value of 0.9 W/m2K). New draught lobby / buffer space created by unheated "clip-on porch". Existing suspended floor insulated (to achieve U-value of 0.201 W/m2K) ; * renewal of existing roof and placement of insulation between and under existing rafters in addition to joist level to create warm roof (to achieve U-value of 0.15 W/m2K). |
| Other relevant retrofit strategies | Low energy lights, appliances, cooking and water-saving devices are also going to be supplied and installed. Despite property being currently void, much of the retrofit can be undertaken with tenants in situ (external wall insulation, installation of Heat Pump etc.). |
| Contextual information | Extension a real opportunity and constraint as it would be built to current Building Regulations. Co-ordination to manage the proposed extension into the existing retrofit undertaken by the team. Will be interesting to see performance differences between new extension and retrofitted existing part of the property. Innovative & intelligent triple glazing system capable of providing secondary heating should heat pump require servcing or fail. Team keen to use the project as a n opportunity to get data therefore additional data logging devices proposed to provide enhanced monitoring feedback to exceed TSB base specification. |
www.retrofitforthefuture.org/viewproject.php?id=136#strategies
