Across Europe, we use a phenomenal amount of energy in the processes of heating, cooling, ventilating, lighting and electrifying the buildings that we use. The iNSPiRe project is a Europe-wide endeavour aiming to drastically cut the CO2 emissions arising from the energy consumption of buildings. With twenty-four different partners from various fields in seven countries, and nine work packages spanning four years, iNSPiREe is now just over a year old and the fruits of the first year’s work are almost ripe.

The latest EU targets for reducing energy consumption in buildings state that all new buildings must be nearly zero-energy by 2020, but also that all existing building stock should have energy consumption slashed to almost nothing via retrofitting. In order to successfully retrofit the entire European stock of old buildings, low-cost solutions will be imperative.  iNSPiRe’s goal is to create packages for systemic renovation of existing homes and non-residential buildings that do not cost the earth.


The third and largest work package deals with the development of envelope solutions for buildings, looking at the layer that divides the outside from the inside as well as factors like daylight supply, heating, cooling, ventilation and general comfort levels. The aim is to develop integrated packages of energy-reducing technologies in the form of external façade kits that can be fitted to existing buildings with minimal disturbance for inhabitants and users.

Fourteen months in, this work package has produced one of the project’s first tangible deliverables: a micro heat pump that integrates into these façades. A team at the Unit of Energy Efficient Buildings at the University of Innsbruck (UIBK), led by Dr Fabian Ochs and working closely with industry partners such as Siko Solar and Gumpp & Maier, are responsible for this innovative new take on the air source heat pump.

The micro heat pump (μHP) works on the same principles as any air source heat pump, using a compressor cycle that exploits the physical heat–pressure relationship to upgrade heat from the cold ambient air source to an indoor space. The concept works either with water-based systems using radiators or underfloor heating, or air-based systems that directly pump hot air into the building. The prototype is an extract air-to-air model in combination with a mechanical ventilation with heat recovery (MVHR), which, Ochs explains, “has the highest potential to be really micro.” The innovative element is the integration factor; because the heat pump must form part of a non-intrusive façade, it is significantly smaller than a typical heat pump, both physically and in heating capacity terms.

The basic concept of compact units – extract air heat pumps, with storage for hot water – has been used in the Passivhaus field for some fifteen years already. The innovative importance of the work lies in separating space heating from water heating, downscaling the heat pump and integrating it into the façade.

The heat pumps range from 1 to 1.5 kWp heating capacity – relatively miniature. They are designed for buildings with high-energy efficiency ratings or Passivhaus or EnerPhit specification, which have extremely low heating demand – in the region of 15-25 kWh per square metre per year. “Cost efficiency is the crucial thing here,” says Ochs. Technical efficiency is not so important because of the low demand.

Another novelty of the micro heat pump is that it works in conjunction with the mechanical ventilation system and a larger heat recovery unit (MVHR), and can use both ambient air and extract air from the ventilation system as the heat source.

One of the great advantages of integration into the external façade, is that almost everything can be prefabricated, so installation causes minimal disturbance. As the micro heat pump shares the system used for ventilation, only one air distribution system is required within the building.

There is a discourse around the issue that the cost of Passivhaus and energy-saving technologies is prohibitive to the majority of people who might benefit most from it. And with ‘eating vs. heating’ a hot topic in many countries in Europe at the moment, this is a pertinent issue. ‘The idea here is to demonstrate that we can provide heat at a reasonable cost”, says Ochs. “Of course you can always do better if you double the cost, but we need technologies that are efficient and well priced.”

The project is well on schedule, the imminent stage being the proof of concept. The prototype micro heat pump, along with the rest of the 2.7×2.7m façade, is under construction by industry partners and will shortly be delivered to UIBK for testing in double climatic chambers (PASSYS test cells), which simulate outdoor and indoor atmospheric conditions. The first stage will test just the ventilation system, and the second will include the heat pump. Later on, acoustic testing will sound out the audible levels of the various mechanisms to ensure no sound disturbance, either to inhabitants or neighbours.

Before the demonstration stage, which will see the façade installed on three or four demonstration flats in Ludwigsburg, the team must convince the social housing company Ludwigsburg GmbH (WB-LB) that the building envelope solution works – and that they can deliver at an affordable price.

As heat pump technology is still fairly new, costs are still relatively high – perhaps because there is not yet enough competition to drive them down. Ochs hopes that the advent of these new, practical products will drive prices down and foster competition as other industry players pick up on the concept of integrated solutions.

How soon these developments may start to benefit the wider public will depend on the level of engagement of industry partners. Once the concept has been proven, a company or companies need to bring it to market. “Going on reasonable expectations of market forces, the project should result in these new technologies becoming available and costs falling,” says Ochs. “But, of course, the market is not always reasonable!” Market uncertainties aside, though, these are undeniably inspiring steps towards a future of energy-efficient buildings.