The conference is organized by Regione Piemonte Building Sector, as a divulgation activity, in the EU Alpine Space ENERBUILD Project. 
Experiences under study will come from public and private bodies, mainly located in the Alpine Region.
Invited speakers are from organizations that build and manage buildings for social housing pourposes, from Regione Piemonte (ATC Torino), North Italy (IPES Bolzano), France (OPAC 38 Grenoble), Vorarlberg Region of Austria (Vogawosi), from public funder (Regione Piemonte), and from other subjects involved in social housing projects (LEGACOOP, FEDEREABITAZIONE).
The Conference will show different strategies adopted by funders and operators dealing with the theme: “energy performances and social housing”, to share know-how and good practices to improve architectural quality, cost reduction, and to generate development and innovation for local actors. Strategies and targets for public funding allocation will be investigated and compared.

SATURDAY 27/11/2010

10.15 - 13.30

Torino, Lingotto Fiere

Hall 3, Sala n° 1 CNA – ENVIPARK

Program

Moderator: prof. Gian Vincenzo Fracastoro - Politecnico di Torino, Dipartimento di Energetica

10.15 Dario Milone - REGIONE PIEMONTE

"Introduction and description of the project ENERBUILD incentive programs for social housing energy efficiency"

10.30 Benoit Jehl - OPAC 38 - Grenoble (FR) Vogewosi - Voralberg (A)

"Experiences, accomplishments and achievements"

Centro Comunale In Voralberg. Edificio Passivo in legno locale

12.10 Egidio Giannico - LEGACOOP

"Esperienze, realizzazioni e risultati ottenuti" – 13.30 Round table and debate

Passiv-haus: some thoughts and guidelines for their design and use

G.V. Fracastoro

When analysing the design of a passiv-haus the first thing which appears clear is that reducing the transmission losses and exploiting at their maximum solar heat gains is not enough: ventilation losses should not be neglected, because they may determine losses in the order of 20-30 kWh/m2 in places with 2500 Degree-days. Reducing the air change rates by adopting very airtight windows (as many high efficiency and low U-value windows are) is not such a good idea, as this would lead to unacceptable Indoor Air Quality (IAQ). “Build tight and ventilate right” (Arne Elmroth) is the rule in these cases. So, in order to provide acceptable IAQ (meaning air which is not only acceptable to olfaction, but also healthy indoor air), a centralized mechanical system is needed provided with a suitable heat recovery system, possibly active or enthalpic.

The second obvious finding is that the behaviour of users becomes a dominant factor on energy consumption. An adequate education of the inhabitants of a passiv-haus may help not only to reduce energy needs but also to improve thermal comfort and IAQ.

The benefit from sola gains should not become a discomfort cause and an undesired extra cooling load for the air conditioning system, if any. This sort of problem become crucial in mild climate areas, and especially in Italy, while it is probably less important in the Northern Europe countries like Germany, where passive houses were first designed and built. Successful technological solutions in Innsbruck may reveal to be unsuitable and disappointing in Bozen (Bolzano), just a few km South from Innsbruck, where some passive houses have evidenced more than 1500 hours above 26 °C in the summer months.

For both heating and air conditioning periods, a calculation tool able to simulate the building behaviour should be available. This tool should be simple, although accurate, even if these two words evidently conflict one against the other. Particularly for summer calculations, the 13790 Standard does not seem sufficiently supported by experimental data.

Once all the measures listed above (good walls and windows insulation, high solar gains, heat ventilation recovery) have been adopted, the winter energy demand will probably be reduced to a few tens of kWh/m2, or a few litres of gasoil, or cubic metres of natural gas. It is no longer advisable to invest more money on the building envelope: every further reduction of the energy demand will have unacceptable costs. One should then start to think of how to minimize the primary energy demand. First of all, the distribution pipes should be well insulated and run within the heated space, control should be accurate “in space and time”, and heat metering devices should be installed in centrally heated buildings in order to increase the energy consciousness of the users.

Heat terminals should possibly be of the “low temperature” type (and high temperature in the summer), such as radiant floors. This will not actually reduce the primary energy needs but will allow the use of low exergy sources as solar energy, industrial thermal waste, low temperature heat from heat pumps, etc.

Last but not least, efficient energy generation is the real key to a low primary energy building: high efficiency conventional systems like condensation boilers, or more high-tech systems such as heat pumps, possibly coupled to renewable energy systems.

Particularly interesting, especially when supported by interesting subsidies on capital costs and feed-in tariffs on power production as in Italy, appears the coupling of ground-coupled heat pumps with photovoltaic (PV) systems. As an example, a building whose energy demand has been lowered to 50 kWh per m2 of floor area, equipped with a ground-coupled heat pump will need 12-15 kWh/m2 of electricity, or 10-15 Wp installed capacity of PV panels for every m2 of floor area, in Central or Northern Italy. A 1-1.5 kWp PV generator would guarantee the energy needs for heating a 100 m2 flat, at a cost ranging from 3500 to 4500 €. Slightly higher installed capacities would also cover the electrical needs of the building (lights, electrical equipment, pumps, etc.). The building would easily become a “Near Zero Energy Building” (NZEB), or even produce more energy than required by its operation.

Social and economic aspects should not be forgotten in social housing, where the question of investment and operation costs is of paramount importance, and is strictly connected to the economic troubles encountered by low income families, thus frequently leading to arrearage problems. A ZEB or NZEB has a higher investment cost than a “normal” building, complying the limits established by Standards and Regulations. A situation where all the extra costs are sustained by social housing enterprises, while all the benefits, in terms of lower utility costs, are enjoyed by the users, is not acceptable. In France, renting costs and energy costs are pragmatically compensated: higher renting costs in exchange for lower utility costs seems to be an acceptable solution, far from being a scandal.