Zero Energy Buildings & retrofitting

Is it possible to turn an existing home (or other building) into a zero energy building?

There are hundreds of millions of existing buildings in need of renovation. It’s a multi-trillion dollars business that can trigger economic growth and lots of employment opportunities…

On the other hand, the energy efficiency of such buildings is also a key environmental issue. Buildings are the greatest responsible for carbon emissions and environmental degradation, worldwide. They consume about 40% of the energy produced in the world – more than the transportation sector or the industry. Global warming and climate change are in large part – even if indirectly – driven by the energy consumption of our homes, schools, offices and other buildings. 

Hence the question: is it possible to turn an existing building into a Zero Energy one?

The short answer is: it varies according to the climate zone and though technically possible in most cases it may be expensive or difficult; what is easy in new buildings, may be difficult in existing ones; there are huge obstacles – related to the cost and the expected recovery of the investment, market failures, funding issues and, of course, difficulties arising from poor design, shape, layout, siting, size, location of the windows and so on…

It’s not enough to replace the existing windows and exterior doors with very efficient units, or to install modular insulation kits on the walls and ceilings (to prevent unwanted heat transfer) of the existing buildings, or to install a large solar photovoltaic system on its rooftop.

All these improvements can be very important, and reduce their energy consumption, but it can be expensive and may not turn the building into a real zero energy one.

While we can take steps and make improvements to turn an existing building into a greener one, it still will not be as efficient (or a true ZEB) as a building built with that intention. Anyway, though Zero Energy goals are mostly an issue for new buildings, it’s possible and advantageous to apply some ZEB methods to existing buildings.

Prefabricated retrofitting kits

It’s easy to spend too much money with energy improvements. The renovation of exterior walls, roofs and windows by using traditional methods can be expensive and with a long payback.

Hence the idea of developing low-cost, multifunctional, modular, easy-to-install prefabricated modules for the facades and roof elements of buildings - integrating them with heating and ventilation equipment or renewable energy solutions, upgrading the whole building and its envelope. The solutions are mostly plug-and-play, easy to assemble (or disassemble, for maintenance).

The goal is to facilitate the on-site work and to reduce the installation time and cost, making energy-efficiency improvements more cost-competitive.

These modules can be designed to respond to the needs of existing buildings, and the companies that are developing these type of materials are claiming a return of the investment in less than 8 years (through energy savings).

The EU ZEB project is promoting this kind of solutions and we list some of them below:

iNSPiRe -  producing systemic renovation packages that can be applied to NZEB.
RetroKit (SINTEF) - develop a retrofit toolbox integrating flexible prefabricated solutions to upgrade existing buildings and their envelope.
MEEFS - Multifunctional Energy Efficient Building Facade System for Building Retrofit
Bricker - System to retrofit existing public-owned buildings; goal: to achieve at least 50% energy consumption reduction

Getting the involvement of the residents And Funding

The success of building retrofitting projects – intended to reduce energy consumption by 50% or more - depends significantly on their scale: individual projects are typically too expensive. On the other hand, getting the involvement of entire neighborhoods or all the residents of a condo or an apartment building is not easy…

All the more that it may also be critical to replace individual heating or cooling, or hot water, or ventilation systems by collective systems, requiring the commitment of local governments, awareness and proper funding.

Funding is especially important. Explaining the advantages and the philosophy of the project is key to get people involved, but without a good financing model, all efforts will fail.

See: Financing models for ZEB



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