Households consume a significant fraction of total potable water production. Strategies to improve the efficiency of water use tend to emphasize technological interventions to reduce or shift water demand. Behavioral water use reduction strategies can also play an important role, but a flexible framework for exploring the "what-ifs" has not been available. This paper introduces such a framework, presenting an agent-based model of household water-consuming behavior. The model simulates hourly water-using activities of household members within a rich technological and behavioral context, calibrated with appropriate data. Illustrative experiments compare the resulting water usage of U.S. and Dutch households and their associated water-using technologies, different household types (singles, families with children, and retired couples), different water metering regimes, and educational campaigns. All else equal, Dutch and metered households use less water. Retired households use more water because they are more often at home. Water-saving educational campaigns are effective for the part of the population that is receptive. Important interactions among these factors, both technological and behavioral, highlight the value of this framework for integrated analysis of the human-technologywater system.

Circular Economy in the building and construction sector is challenging the conventional habits and models of work. It demands comprehensive collaboration between stakeholders and collaborations even with unconventional partners. Nevertheless, circular economy model can give remarkable opportunities to tackle the climate change with the help of building and construction sector and helps to find sustainable solutions to the growing urbanisation and to expansion of the cities. Very crucial obstacle in order to implement circular economy into building and construction sector’s processes is the sector’s difficulties to adopt new methods. This includes difficulties to use new recycled materials and building components, legislation obstacles, contract models do not support circular economy solutions etc. Often these obstacles are result of absence of life cycle thinking and coordination. Key to solve these kinds of situation where no stakeholder alone can take the responsibility is to gather all the stakeholders together and boost them to solve these cross sectoral obstacles. To support the adaptation of circular economy into Finnish building and construction sector, The Finnish Innovation Fund Sitra launched a project “Circular Economy in the Built Environment” in the beginning of year 2018. The coordinator of this project is the Green Building Council Finland. Target of this project is: 1. To increase the knowledge on circular economy on the construction and building sector 2. Define how we can support circular economy in building and construction sector and what indicators we can use to authenticate this development 3. Create new collaboration between different stakeholders 4. Develop the procurement and designing processes The project started by identifying key persons that can advance circular economy in Finland in the building and construction sector. These key persons were asked to point out more circular economy professionals. The project succeeded to collect a network with hundred professionals. With this network and workshops, we defined what circular economy means in build environment and what is our common targets in the implementation of it. As a result, in the project we defined seven imperative targets that must happen in the building and construction sector. These targets are: 1. Construction and building sector have a common goal to advance circular economy 2. Norm and regulation steer strongly to circular economy 3. Renewing the habits 4. Life cycle thinking is the starting point of all planning and design 5. Areal planning advances circular economy 6. Procurement support circular economy 7. All spaces and locations are in maximal use In the project we also defined action proposals how to achieve these targets. As a conclusion we argue that achieving circular economy targets and actions that the whole sector is ready to implement willingly demands common work and the will to work together must come from the stakeholders themselves. Different stakeholder has different motives, but this does not prevent collaboration if there is a neutral platform where to co-work with colleagues.

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