Eco-neighborhoods

A sustainable approach to urban development (part 2/2)

Info: Αρχιτέκτων/πολεοδόμος, υποψήφια διδάκτωρ ETH Ζυρίχη

Achieving eco-neighborhood projects in Greece

Part 1 of the eco neighborhoods article asked: what are eco-neighborhoods? and provided some inspiring examples of projects successfully implemented by Northern European nations.

Part 2 focuses on how we can apply environmentally responsible urban development and especially so in Greece.

Realizing eco-neighborhoods

The proliferation of eco-neighborhoods in Europe demonstrates a paradigm shift in urban development practice towards environmental sustainability. However achieving sustainability at the neighborhood level requires the participation of many actors from the public and private sectors, as well as a favorable political and economic climate. We can distinguish between:

–       Solutions heavily dependent on public control, including zoning regulations and local planning, such as density, mix of uses, transportation options, energy systems

–       And solutions more easily achievable through private initiative, particularly innovative aspects of building construction and small-scale energy production.



Of course, the two are not mutually exclusive. Private initiatives depend on public regulations, subsidies, partnerships etc. Equally, private development trends influence public planning processes. This distinction between public and private is useful in the case of Greece, where the public planning system is weak and therefore environmental innovation largely depends on private initiative. In this respect, an area with great potential is green building construction.

Green building construction: the rise of passive houses

Energy efficient building construction features in all eco-neighborhood projects, but Vauban, an eco neighborhood in Freiburg, Germany, is perhaps where it was most intensively sought, as witnessed by the widespread adoption of the “passive house” standard (Passivhaus) thereafter.

The Passive House Institute in Germany defines the passive house as “a building, for which thermal comfort can be achieved solely by post-heating or post-cooling of the fresh air mass, which is required to fulfill sufficient indoor air quality conditions – without a need for re-circulated air”. In other words, a building in which a comfortable interior climate is maintained without active heating and cooling systems. Technically, the peak heating load for a Passive House should be projected to maximum 10 Wh/m2. Up to this point, a simple ventilation system is sufficient for space heating and cooling. Higher energy efficiency goals lead to dramatically increased construction costs. For northern European climates (between 40 and 60 degrees latitude), this threshold translates to an annual heating requirement of less than 15 kWh/m2a, and a combined primary energy consumption of living area of less than 120 kWh/m2a (for heat, hot water and household electricity).

The EU project SECURE ( Sustainable Energy Communities in Urban Areas in Europe, 2008) provides a good summary of the basic features that explain passive house construction:

Compact form and good insulation Insulation of all components of the exterior shell to achieve U-factor < 0.15 W/m2K
Southern orientation and shade considerations Large glass surfaces, greenhouses, double walls etc. for passive use of solar energy in the winter, and shading elements for the summer
Energy-efficient window glazing and frames U-factors < 0.80 W/(m2K) and solar heat-gain coefficients around 50%
Building envelope air-tightness Air leakage through unsealed joints < 0.6 times the house volume per hour
Passive preheating of fresh air Fresh air brought into the house through underground ducts that exchange heat with the soil; fresh air preheated to at least 5°C, even on cold winter days
Highly efficient heat recovery from exhaust air Air-to-air heat exchanger; most perceptible heat in the exhaust air transferred to incoming fresh air (heat recovery rate > 80%)
Hot water supply using regenerative sources Solar collectors or heat pumps for hot water
Energy-saving household appliances Low energy refrigerators, stoves, freezers, lamps, washers, dryers, etc.

Of course, not all energy efficient houses need to be passive houses. But the ecological and economical benefits of passive houses are substantial. They cost 10-15% more to build than conventional houses, but this cost is amortized within a few years due to the heating energy savings. Further, passive houses have a minimal environmental footprint, particularly when passive features are combined with ecological construction materials and other resource saving measures.

Passive house in Vauban. (passivhaus-vauban.de)

Potential for green developments in Greece

So far, the vast majority of eco-neighborhoods and projects have been constructed in Northern Europe. This can be attributed to a combination of technical capacity, favorable regulations, and a strong planning culture, particularly for large-scale projects.

In Greece, environmental awareness about urban development has been slow to pick up. The disconnect between building regulations and local government planning, along with a general incompetence of state planning mechanisms, have led to a minimal control of urban expansion, let alone the implementation of environmentally-friendly urban features. Green building construction also lags behind, as mentioned in the first article of the column, due to a combination of developers’ reluctance to invest, engineers’ poor know-how, a deficit in end-users’ awareness and lack of financial incentives.

However, there are positive signs of change. Residents are starting to appreciate not only the environmental value but also the economic sense that energy efficiency makes. Some Greek municipalities are getting involved in European programs for sustainable cities that aim to improve public spaces, transportation networks, building efficiency and encourage green mobility in addition to local environmental protection. At the national level, new building regulations make energy calculations imperative and incentivize the implementation of some features of passive architecture (such as double facades and greenhouses). Nevertheless there is still a long way to go.

The current economic crisis may be seen as an opportunity rather than an impediment to innovative green urban development. With building activity at a historic low, this is a good time to plan for sustainable building and urban development for the future. Further, industries with promising financial savings, such as green building and green transportation, offer great potential in light of rising oil and gas prices.

Passive houses in particular are still an unexplored technique in Greece. As of 2010, there were approximately 25,000 certified passive houses in Europe, the majority of which in German-speaking countries. But a passive house has the potential to become a popular concept for at least three reasons:

1) Individual homebuyers, who occupy an important share of the Greek real estate market, are likely to seek long-term savings.
2) The climatic conditions in Greece make the implementation of passive measures for winter solar gains easier.
3) The economic crisis has instilled a desire for cost savings in construction, which is too pricy in comparison to other European countries.

Indeed, passive houses and energy efficient construction in general are gaining ground. Within the last couple of years, a number of events and talks have been organized. The first certified passive house in Greece was built in the Penteli suburb of Athens in early 2012. A team of engineers in Ioannina, a small city located in Northern Greece, is planning EcoOiko, a passive house that will also feature a unique design and other resource saving measures. Finally, the Hellenic Passive House Institute was founded a few months ago in order to promote the Passivhaus standards and methodology in the Greek market.

Design sketch for a passive house planned in Ioannina (EcoOiko)

Although we should probably not expect to see municipalities and private developers embarking on innovative eco-neighborhood projects in Greece any time soon, there is certainly potential for smaller-scale innovation that may eventually add up to a more sustainable planning and building practice nationwide.

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