project advies: energieneutraal – klimaatneutraal – systeemneutraal – (=circulair)

In een recent project is bovenstaande driedeling in ambities  ontwikkeld en uitgewerkt. Vanwege de  nodige vragen hierover,  is er een korte toelichting geschreven.

toelichting e-k-s neutraal – circulair bouwen okt 2016 rorovers

Geïnteresseerd? : Een lezing of workshop met uw medewerkers met vele voorbeelden en keuzedilemmas , om dit verder toe te lichten of uit te werken voor uw organisatie of onderneming. Meer info:


Housing corporation award jury

At the National Dutch congress “Sustainable built” , a award will be given to housing corporation with the most creative approach regarding climate change.  As member of the jury I was asked to give a a impression of the implications of  climatechange ambitions.  It has been published as a column on the conference website (in Dutch) :

The congress and award ceremony is 16 November.



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:





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