Totnes Passivhaus

UK Passivhaus Awards 2013 Residence of the Austrian Ambassador, London4th July 2013

Totnes PassivhausPrivate Housing

Passivhaus Homes Ltd.CTT Sustainable Architecture, Williams & Partners

Awards Sponsored by:


UK Passivhaus Awards 2013

Awards Organised by:

Totnes Passivhaus – Passivhaus Homes Ltd.

Project Overview

Name: Totnes Passivhaus

Type: Single family dwelling house with B&B

Build type: Cavity wall masonry retrofit using an External Wall Insulation System and a new-build timber-frame extension with living roof, natural and high performance materials.

Location: Totnes in South West England

Occupancy: Occupied since August 2011

Construction Costs: £1400/m² gross or £1475/m² net floor area

Totnes Passivhaus North Elevation





Project Overview

Project Team

Client:

Adam Dadeby and Erica Aslett

Architect:

Janet Cotterell of CTT Sustainable Architecture

Consultants:

PHPP Adam Dadeby

Contractor:

Jonathan Williams of Williams & Partners

Certifier:

Peter Warm of WARM: Low Energy Building Practice





Measured Energy Performance

Primary Energy Demand 68kWh/m² predicted by PHPP

Annual Heat Demand: 13.3kWh/m².a

Heating and cooling Load:9W/m² heating 4W/m² cooling

Airtightness at Certification: 0.2 a.c.h.

Total Primary energy in use 76kWh/m² as measured in use

51kWh/m².a (electricity)25kWh/m².a (gas)

This small uplift from predicted reflects both running a home office and the B&B

PROJECT ‘U’ VALUES:

Exterior wall 0.1 W/m²K

Roof 0.1(average) W/m²K

Floor 0.2 W/m²K in retrofit 0.08 W/m²K in new-build

Windows 0.75-0.93 W/m²K

Doors 0.79 W/m²K

PROJECT FORM FACTOR:

Optimising the form factor – 2.62 (external area/TFA)

This has a significant effect…

Typical range from say 2 to 4

VENTILATION STRATEGY:

Paul Novus 300 - located in roof space off en-suite

‘Lindab Safe’ ducting

HEATING STRATEGY:

Post heater to warm the incoming air

LEARNING: Effect of cooler ground floor and

MVHR location

SHADING STRATEGY:

Blinds integrated into window – lower ‘U’ (0.93W/m²K)

Helped with planning constraints, but milder climate





Internal Environment

GLAZING

Lots of large windows ensure the house has a bright and light interior

– even on the north façade (the garden façade) we managed a large

fixed picture window.

INTERIOR TEMPERATURE is sensitive to the use of the integral

blinds – effective shading is essential. Temperature fluctuations happen

slowly, although 150 visitors at Totnes Eco Open House did have an

effect!

Initial problems with the in-line duct post heater meant that during the

first winter a small oil filled electric heater (400W) was used to heat the

three storeys to 19°C – imagine if this was NOT a Passivhaus…

During November 2011, while other nearby houses had already started

using their heating systems the Passivhaus windows were still being

opened - the ‘window opening season’ is definitely longer in a

Passivhaus

MVHRFilters are currently being changed every four months (an indicator

shows on the control unit located in stairwell) – only a five minute job.

The overall unit draws just 40W (circa 1KWh/day or 15p). The user

interface is not as ‘friendly’ as it could be, although mainly simply left on

the standard setting (its easier to open a window!). A lot of frying occurs

with the B&B and there has not been a need to boost the ventilation.





Internal Environment





Occupant FeedbackSuzanne & David, London, Nov 2012

“Thank you for your warm hospitality and for

being our first real experience of a passive

house – very inspirational!”

Juliet O., October 2012

“Fabulously comfortable. Thank you.”

Karin & Rob, Yorkshire, August 2012

“Thank you for a great stay in a wonderfully

designed Passivhaus. It has been inspirational!”

Bruce H. & Sarah W., January 2012“Amazing Passivhaus!” “Great place – all houses

should be like this! Thanks for the warm,

friendly welcome.”

Jonathan & Susie P., Devon, Jan 2012“Wow. What a comfortable experience!

We will be back for more. Thank you”

“Such a comfy bed and delightful view;

so grateful to experience Passivhaus in reality!”





Design Philosophy/ Innovation

The house forms part of a 1970s modernist estate so the design had to address the perceived ‘group value’. Overhanging eaves or prominent shading devices were not acceptable to the planners and the roof form, orientation and finish result from the context.

We used a combination of high performance materials (as dictated by the performance needs of the retrofit) and a ‘natural materials’ led design for the new-build element.

Estate architect was LEONARD MANASSEH and is referenced by PEVSNER two or three times

The original dwelling Adjacent dwellings, group value & style

Totnes Passivhaus





Design Philosophy/ Innovation

Foamglas pillars

900mm apart

around perimeter

Addresses the perimeter

thermal bridge, with a

relatively conventional

foundation detail that uses

conventional builders

skills – although ALL work

needs doing with some

precision

Steel penetration

through the airtight

layer - welding into

the web and taping.

In 2010 we were

trialling a lot of

these details in the

UK…





Aesthetics – part of a 1970’s modernist estate where the ‘group’ value needed to be maintained





Aesthetics

Central staircase The living roof





Other sustainability features

Living Roof

The new timber-frame extension has a living roof which was modelled in WUFI by Ecological Building Systems to ensure any potential condensation issues were addressed for a timber and highly insulated envelope…

Solar Hot Water and PV Array

Photovoltaics – Moboasolar panels, total 3.99kWp, Fronius IG TL transformerless inverter; solar hot water – Rotex 500 litre thermal store with 9.4m² of integrated roof panels

East and west

facing – loss in

performance

about 20% effect





Costs

Construction costs

£1475/m² net floor area £1400/m² gross

Extra construction costs

Extra over Adam estimated at 10% covering uplift for Passivhaus specific items such as high specification windows

Planning costs

There were costs relating to re-working to suit the planning constraints –orientation, windows, shading

More than half total spend in local and SW

England economy





Outcomes…

The Passivhaus HandbookThe project demonstrated the importance of effective team-working and finding common goals

and the need for a practical and accessible book on the subject, now realised through Green Books.

‘Could not think of a better book to cover this subject. Well thought out.

Well written. Useful illustrations. Excellent tables and specific interest

segments.’ M.H. Denekamp, June 2013

‘This book is very informative without being too technical, so suits

professionals as well as those considering commissioning a Passivhaus

design. Highly recommended.’ Martin Smart, April 2013

Optimised Timber Portal Frame SystemSimplified for affordable new-build – first prototype

air tight test next week (July 2013). Options PH15 and PH30

Adam’s PROJECT BLOGA great online resource and continues to receive positive feedback from Passivhaus enthusiasts.http://passivhausrefurb.blogspot.co.uk

http://passivhausrefurb.blogspot.co.uk/

Documents

Totnes Passivhaus