“It is no longer new but it is still innovative,” says Jon Boorland, chief executive of the Passivhaus Trust. The zero carbon approach to construction is moving into the mainstream, aided by the growing body of evidence for its financial viability, health and environmental benefits. The Passivhaus Trust is talking to a number of UK government departments about how the whole building sector could move to Passivhaus or equivalent by 2030. “We are about to enter a tipping point,” says Boorland. With plenty of tipping points nearing for climate change, this one would be very welcome.

In the UK, more than 1000 buildings have been completed to Passivhaus standard, with another 1600+ under way. Around the globe, they are multiplying in number and diversity. The highest Passivhaus building is now the 28-storey Bolueto Tower of 361 social housing apartments in Bilbao.

This would be exceeded by a proposed development in Vancouver of a two-tier 43 and 48-storey residential development at 1400 Alberni Street, touted for completion in 2022. The Canadian city has a target of no greenhouse gas emissions from all new buildings by 2030.

In China, the largest Passivhaus residential district in the world is under construction, in the city of Gaobeidian. On completion, it will span around one million square metres of living space (the city will also host the 23rd International Passive House Conference in September – see events section here for details).

Many other new buildings in China are also being built to the standard, including in the cities of Tianjin, Beijing and Qingdao. In Germany, the world’s first Passivhaus hospital is under construction in the Frankfurt district of Heochst. Given the health benefits of the approach, could this become the norm for hospitals and other health institutions in the future?

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The world’s first Passivhaus hospital under construction in Frankfurt

The Passivhaus approach can also be applied to existing buildings. An example was a project at a nursing home in Dun Laoghaire in Ireland. The existing building was a 1970s two-storey block of 34 apartments. An additional floor was added and there was retrofitting of the existing building fabric involved external wall insulation and Passivhaus certified windows.

Cornell Tech Tower

On Roosevelt Island in the East River in New York is the Cornell Tech Tower. At 26 floors and comprising 350 student dormitory units, it was the world’s tallest Passivhaus building before being pipped by Bilbao.

“It is probably the most energy efficient tower in North America by a long shot,” says Tomás O’Leary, co-founder and CEO of the Passive House Academy, which specialises in training, certification and consultancy and was one of the partners on the development. It was involved in the Dun Laoghaire project, mentioned above.

Air tightness is, of course, key to Passivhaus. “Effectively you are building a submarine and you don’t want to be the person responsible for a leak,” says O’Leary. In New York, much of the development of the tower was done offsite and then brought in by barge, including the insulated triple-glaze windows. While the air tightness involves effort and new techniques, with a strong emphasis on a high-performance façade, polymer sealant blown through the ducts, and highly efficient indoor environmental systems, the gains are significant.

For one thing, reducing the heating and cooling demands by 90% means jettisoning a lot of the heavy equipment that would normally be needed. The Cornell Tech Tower, for its 526 occupants, has four modestly-sized ventilation units. The estimated annual CO2 saving is 882 tons, equivalent to planting 5300 trees.

New York’s wide average temperature range, from 23°F (-5°C) in winter to 86°F (30°C) in summer was among the challenges on this project when it came to creating energy recovery ventilation and low-energy heating and cooling systems to provide year-round air quality and temperature control. The window-to-wall ratio is 23% and the building faces south, with relatively narrow east and west facades, which is ideal, says O’Leary.

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Cornell Tech Tower in New York

Exeter’s new leisure centre

In the UK, Exeter City Council has been a pioneer, with more than 100 Passivhaus homes built in the last ten years, mostly for affordable rent. Since completing its first multi-residential scheme in 2010, all of the council’s new-build residential projects have been to Passivhaus standard. Of those tenants who have been living for more than eight years in these developments, 60% have never had to turn on the heating, says Emma Osmundsen, development director on the council.

The council’s three principles are for developments to be financially viable and socially and environmentally responsible. Only Passivhaus delivers on all three, says Osmundsen. It wants all buildings to be climate-ready, she adds, and “cast-iron low-energy”.

The council is now building the UK’s first and the world’s third Passivhaus leisure centre. The development is under way and on target for opening at the end of 2020 at St Sidwell’s Point, on the site of an old coach and bus station. This urban regeneration development includes a new coach and bus facility and a large-scale mixed development.

The council is adopting the leisure centre standards of the Passive House Institute in Germany as there is currently no equivalent in the UK (the other two Passivhaus leisure centres are in Bamberg and Lünen, both in Germany).

The new facility in Exeter will include a 25 metre competition swimming pool, 20 metre community pool, learning pool, 150-station gym, soft play area, café and crèche, plus health and spa facilities, with a total footprint of around 900 square metres. The budget is £35 million, within an overall £300 million regeneration (of which £250 million is private investment).

Adopting Passivhaus made business sense, says Osmundsen. Leisure centres are typically “energy-guzzling” with a wide range of temperature zones and high humidity. The estimate is for a 65-87% saving on overall energy use. In terms of air tightness and high performance windows and doors, these are equivalent to a Passivhaus house and the building has been designed for optimised solar orientation (40% of the south-facing glazing is for the wet areas).

However, Passivhaus is also about quality and comfort, not just energy use, says Osmundsen. The facility has been modeled to withstand predicted changes in climate conditions to 2080 and, due to the highly efficient filtration, the pools will have excellent water quality, needing minimal use of chemicals, including chlorine. A significant reduction in evaporation in contrast to a standard centre will also mean much lower water usage (perhaps 50% less).

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Architype’s Ann-Marie Fallon

All of which means cost savings plus an expectation that there will also be an income benefit because the attributes, combined with exceptional air quality, is likely to mean more visitors and longer use of the facilities. Staff will also clearly benefit from the comfortable conditions. Usage could increase by 10%, which is factored into the predicted business case, on top of the estimated savings from energy reduction and lower maintenance of £200,000.

The challenges

In many ways, the developments that have been completed are ideal for heading off the often knee-jerk conservatism of many public and private developers. However, more responsibility for developers related to performance would help to focus minds. There is too little energy accountability in construction, says Ann-Marie Fallon, associate at Architype, London-based sustainable buildings architect firm. Many buildings end up using three-to-five times as much energy as intended. “It is all about developer margins… there is a lack of focus on the occupants’ wellbeing,” she says.

There are 335,000 people in London classified as in fuel poverty. Only 7.7% of these are in properties with an Energy Performance Certificate (EPC) rating of C or above, says Fallon. Using Passivhaus for affordable homes would go a long way to addressing this for new-builds, with the added health benefits on top.

There is also still a need for better understanding of the costs and benefits among decision-makers, plus a need to ramp-up skills. But with every new project, the expertise pool grows. For the Cornell Tech Tower, for instance, the builders, architects, mechanical engineers and others had never previously worked on a Passivhaus development.

When listening to the advocates and when looking at the flagship projects that have been delivered or are on the way, the question with Passivhaus is more, why wouldn’t you adopt it? That tipping point cannot come too soon but the approach feels as though it is edging into the mainstream.