Passiv Shorts

Three architects describe their ground-breaking Passivhaus projects

Susan Venner  (VennerLucas Architects)
On Sunnylands, a hybrid zero carbon house in the Scottish Borders

Sunnybank is a new family house designed to meet PassivHaus standards of energy efficiency and achieve as low an environmental impact as possible.

The building sits on a south-facing hillside, with a regular plan with minimal surface area for heat loss. All the main rooms face south to optimize daylight and views over the countryside. The lower ground floor is the main living space, designed to form a direct relationship with the garden.

We used the Passivhaus planning package (PHPP) to achieve an optimum balance between thermal insulation and solar gain. The electrical demand is minimised and photovoltaic-thermal micro-generation and mechanical ventilation and heat recovery (MVHR) meets the total annual electrical and thermal demand. It is a hybrid approach, amalgamating photo-voltaics and passive solar with Passivhaus principles, together aimed at producing a zero energy building. Working on the design required careful and disciplined construction detailing while on site management was essential to achieve the high build quality required to meet the Passivhaus standard.

Aspects of the pv-thermal passivhaus amalgam approach was client led. The clients wanted photo-voltaics to help with the building attaining carbon neutral status. There is a 26/30 pv array installed with the intention of both offsetting electricity consumption and producing and selling electricity.  VennerLucas are conducting research on the Sunnylands hybrid model. To date monitoring is supporting passivhaus claims.

4orm’s Stephen Coleman
Outlines the first Passivhaus terrace in Highbury, North London to receive certification

This terrace of five Passivhaus replaced an undistinguished commercial building in the residential Highbury Conservation Area adjacent to a fine listed Georgian terrace. None the less consent was initially refused and our preferred scheme built only after winning a planning appeal.

The north facing street elevation of horizontal iroko boarding and storey height windows all held within a white rendered box frame hovers over the dark brick garden walls extending from the rear gardens of the adjacent Georgian terrace. The mostly glazed rear (south) elevation includes user operated retractable external venetian blinds to reduce solar gain.

Internally the houses are simply and generously planned around a top lit staircase. Each with tv room/games den in the cellar, a double height family space overlooking the private enclosed garden to the south, bedrooms and roof terraces to upper floors.

The 3,000 sq.ft houses are built with solid timber Brettstapel panels at a generous 6 metre centres to party walls over a concrete basement. The envelope utilizes; triple glazing (U value 0.7 W/ m2K), high levels of insulation with 200mm recycled newsprint to walls (U value 0.15 W/ m2K) & PIR rigid urethane insulation to roofs (U value 0.17 W/ m2K). The air tightness tests ranged from 0.4 – 0.6 h-1. Each house has rainwater harvesting feeding WC and laundry, whole house ventilation with heat recovery and 4kW ground source heat pumps for heating and hot water providing extremely high levels of air quality and comfort.

Following completion in November 2010 the first occupants arrived off the plane from Sydney. After the coldest three months for over fifty years their utility bill including all energy costs were around £8 a month “for the only comfortable house we’ve visited in London”.

James Anwyl
From Sussex Passivhaus specialists, Eurobuild, writes about the Rural Regeneration Centre at Hadlow College, Kent, the first certified Higher Education building

The Rural Regeneration Centre for Hadlow College, Kent by Eurobuild is the first certified Passivhaus educational building in the UK. Eurobuild inherited the project after planning approval was unsuccessful for an iconic sustainable building. The building was intended as a new teaching facility for the agricultural students and occasional local community use. Eurobuild changed the location to a number of redundant cow-sheds using the footprint (and some walls!) on the College’s fully operational dairy farm. Over 95% of the original shed structure was retained on site and a significant proportion was screened and used for non-structural backfill.

The building’s main purpose is to enable seminar-based teaching, with a staff office and meeting space alongside a significant exhibition area. One of the spaces required by the College was a semi outside space called the ‘Wet Working Area’. Here a sliding window from the main seminar room allows students to watch machinery and livestock demonstrations as part of their studies.

Constructed of super-insulated closed panels, the structure was planned using BIM (ArchiCAD) and assembled in just three days and the structure was airtight to a very high standard of 0.34 h in ten days. A monitoring system has been installed to track the energy consumption of the building over the next two years and beyond for Eurobuild to learn from the ‘as built’ building performance in relation to weather and usage patterns. The building employs a number of sustainable technologies including a Drexel & Weiss mechanical ventilation with heat recovery pump; triple glazed windows; and a ground source heat pump for heating & cooling, waterless urinals, low flush toilets and timed water-saver taps.

Natural slate laid on the screed gives a depth of 70mm, whilst the medium density concrete block walls increase thermal mass and absorb the solar gain from the large south facade. Individual window pergolas and a colonnade across the south façade prevent overheating in summer — all solar modeled in 3D ArchiCAD, checked with TAS software and backed up by the PHPP analysis.

All the timber used in the project was derived from FSC sources or from sustainably managed forests in Austria and apart from two 1m lengths of steel section (100 x 50) there is no metal in the superstructure. This was a conscious decision in planning with respect to life cycle and embodied energy. The panels use recycled ‘blown’ cellulose insulation and were made in Eurobuild’s partner factory in Austria and transported directly to the site near Tonbridge, Kent.