Consists of a typical traditional, 15 dwelling building, 1095 m2 situated in an old district of the city of Vevey, near Lausanne. It is an old ma-sonry non-insulated building, built in 1932 owned by RP and the dwellings are rent in the medium-low sector of the market (190 €/m2 compared to 250€/m2 of the medium-high rent sector) The early studies to establish a refurbishment strategy started in 2016 and the project will be developed and submitted to the authorities in 2017.

The works are planned for 2018. The major stake of the building manager is to refurbish the building envelope reaching the NZEB standards with the chal-lenge of affordable solutions in the framework of restricted investment budget, guaranteeing the financial sustainability (building value and rate of return), with attractive IEQ conditions, rents and energy bills for the tenants.

The last significant refurbishment happened in 1979. Façades present traces of deterioration and the windows are obsolete. Technical installations reach the end of their life span and present serious problems. The envelope is not insulated (Uwall > 1.5 W/m2K, Wwin > 2.8 W/m2K, W roof > 1.5 W/m2K). The ventilation system is simple extraction in service rooms with stack effect vertical ducts. Energy consumption is 187 kWh/m2y for heating and hot water, produced by a central gas boiler.

The refurbishment service, following the sustainable development strategy of the company, has an ambi-tious energy transition program targeting the high energy consumption buildings. The architectural quality and technical constraints of this particular building make external envelope insulation without thermal bridges difficult and expensive. Thick insulation around the windows may reduce lighting.

These constraints make thin insulation interesting and cost effective. Preliminary analysis showed also that a simple demand control ventilation system with or without heat recovery of the extract air to preheat hot water may be also reduce cost for similar energy saving results of solar preheating. Monitoring IEQ and Energy before, during and after refurbishment to control building services and avoid bad user behaviour is also a key objective in order to avoid performance gap observed in other NZEB refurbishment operations.