Retrofit: Energy-saving or energy-generation?

Just published : our research into the optimal balanced materials package for 0-energy building retrofiit, ZEB . As previous exploring research already showed regarding renovation for row house: better insulate less and add some more PV panels. (B in left graph) . In other words, passivehouse is not the optimal choice from materials perspective in case of 0-energy and beyond. The operational energy in all cases is not relevant since all cases are ZEB: its the materials input that determines the most optimal solution, since that is the fossil energy based impact remaining for a ZEB. This paper shows the results for row houses and detached houses, both calculated for 4 alternative packages.

Preparation of Articles for the Symposium Report Preparation of Articles for the Symposium Report

Ritzen,M., Haagen T., Rovers R., Vroon Z., Geurts C., Environmental impact evaluation of energy saving and energy generation: Case study for two Dutch dwelling types Building and Environment, Volume 108, 1 November 2016, Pages 73–84

for some backround on the MAXergy methodology , visit

for some background on the new situation for building evaluations after eliminating operational energy impact, see Rovers R., Zero-Energy and beyond: a paradigm Shift in assessment, Buildings, 5 (1) (2014), p. 1-13


Participating in PhD defense at TU Berlin

Living in cities has the risk of being trapped when systems fail: how to survive? Cities have faded away from their resource base, and consume far above the carrying capacity of their regions , and combined, beyond that of the earth. How to address this ?

deflander defense

Katleen deFlander did her research just on this issue, working at IASS in Potsdam and doing a doctorate at the TU Berlin. As external supervisor I was able to take part in the discussions on theory development, and in her final defense last week. Her analyses found that cities became closed systems (tree structured cities ; ecocities are gated communities of the future ) , while resource cycles opened widely: infinite supply . While the solutions point at a ‘ open cities and closed cycles’ situation, mutually supportive. A interesting work, were small ‘shocks’ could create changes in the right direction, in any case provide a window to try to re-create the way a city is functioning. Though small shocks might not be enough, it requires major shocks and changes, but at least we will know how to act then.

The full work will soon be available, but expert workshops and dialogue workshops added to the fact finding an theory building. See some of these reflections here:





Int. iiSBE Master cooperation Sustainable Building

masters meeting

For some time a few universities work together under iiSBE umbrella in developing master courses in Sustainable Built Environment. The key universities are  UMinho, based in Guimaraes Portugal, and Czech Technical University in Prague.  Others are associated or affiliated to this process.  A major enabler was a EU program I coordinated called  Ides-Edu [1],  in which 15  universities joined forces in developing course material.  and iiSBE ,with many academic members,  as the independent NGO partner for Sustainable Building,

During the SBE16 Conference in Prague, CESB16 , we have  taken initiatives to broaden this cooperation,  Ways of cooperation were discussed ,  as well as a detailed exploration of getting involved with  a few interested universities. Some had expressed interest during my visits , and were represented by a professional in student and teacher exchange organisation . (  interested universities came from Ukraine , Ireland and Australia).  In the next months the structure of cooperation will be further explored and detailed. Interested universities can of course bring forward their interest , via me ( as advisor for master course development) or  the  coordinator of the running joint masters, Luis Braganca from Portugal.


2) picture: the gathering in front of Comenius statue,


Lectures at RWTH Aachen

RWTH poster

The RWTH Aachen  has kindly invited me to give a series of lectures. The Title of the series will be: “Living happily forever on the planet earth” . Starting with exploring a happy planet, the presentation will build a case around the need to go from carbon bomb building to vegetarian building, and the way we could survive in Scar-City, a environment without own resources. To end with the importance of land, our most valuable asset and capital of the future.

The lectures are planned for June 1st and June 15, see the Poster the university has prepared for the details.


prefab and reuse from Greek history

Last week I traveled Sicily , and visited some interesting sites from the Greek & Roman period.

greek quarry iAWglgXAAA_CE4

First of all a quarry, with column elements (unused) for a Greek temple : Amazing how big these elements are, and I realized this could act as a reference for prefab construction, and for 0-fossil fuel production as well , since made only with labor investments…. (not counting labor for Embodied energy…)


But even more astonished I was when visiting the Duomo in Syracuse: I knew a mosque that became a church , the famous Mesquita in Cordoba, Spain, but here I ‘found’ a much older Greek temple preserved as church ! Somewhere at the end of the Roman period it was reused as a church, by closing the openings between the columns with masonry, and redecorating the church from inside. This way it more or less has become the best preserved Greek temple , since the columns and friezes are not a rebuild construction, as in most historic sites , but still standing! Already 2500 years. Unique! And is a reference for long term reuse of buildings….




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