By Susana Toboso (UAB), Xavier Gabarrell (UAB), Gara Villalba (UAB), Cristina Madrid (UAB), Ramiro Gonzalez (UAB) and Caroline BINI (Groupe One)

Perception of the product and the facility (neighbours, residents of nearby buildings)

1.Follow-up survey of different stakeholders, users, and residents nearby the greenhouse. Hydroponic or soilless crops are commonly used in this case because they easily adapt to rooftop constraints (e.g. the weight capacity of floors). However, the acceptance of the produces derived from this system is controversial because European laws do not consider them as ecological farming. Therefore, consumer acceptance of this kind of local food should be considered. See an example about the assessment of taste by potential consumers and their perception in this published paper. This paper seeks to answer two main questions, among others:

  1. How do consumers perceive the quality of the products grown in soilless rooftop farming systems? and

  2. How do consumers perceive soilless production systems for rooftop farming?

The complete survey included 27 open and closed questions and was structured into four sections.

FIGURE Social Aspect.png

2. General information: this section included closed questions (i.e., multiple choice questions) about the socio-economic profile of the participants – age, gender, level of schooling, profession, and income. These data were collected for statistical analysis purposes.

3. Perception of the product quality: this section consisted of closed questions that evaluated different aspects of the quality of the product, i.e., aspect, texture, size and flavour, and ripeness. The Likert scale method can be used for rating each aspect. This scale is a psychometric response scale primarily used in questionnaires to assess the subject’s perception and usually proposes a 5-point scale (ordinal data), assigning a numerical value to each level. For example, 5 answers were proposed to the question “How do you rate the state of the tomato you have eaten?”: “very good”, “good”, “acceptable”, “bad” and “very bad”.

4. Product sale: this section included closed and open questions about the motivations and preferences for purchasing food products from soilless cultivation systems from rooftop greenhouses (RTGs), including willingness to pay, preference for a type of packaging, preferred sales channel, regularity of purchase, and environmental information about the product. This third section was only proposed in the second campaign to collect tips about how business models should be focused.

5. Final comments: the survey ended with an open question referred to the food production and supply methods, i.e. “Do you want to add other comments or opinions”?


Different methodologies are available to calculate social indicators, some more complex than others. Therefore, it is recommendable to differentiate between two groups of installations:

  1. Small rooftop greenhouses (RTGs) for self-sufficiency: short list of easy-to-measure indicators

  2. Large commercial RTGs: social life cycle assessment (SLCA)

on the right : SLCA levels

FIG II 11 6.png

For small RTGs intended for self-sufficiency, a relevant list of social indicators will be advisable. These social indicators should be easy to measure and can be quantitative or qualitative. Therefore, an SLCA is not recommended because many data will be required, and they will be difficult to obtain. Moreover, it is advisable to decide about the social indicators that will be measured based on residents’ interests during the participatory pre-project process with the residents.

Some of the proposed social indicators are:

  • Coverage of residents’ diet (in % and/or absolute values)

  • Maintenance investment (hours/household/year) (Toboso-Chavero et al., 2020)

  • Community engagement- Organisational support for community initiatives, using questionnaires/interviews) (Benoît-Norris et al., 2013)

  • Local Employment (in % and/or absolute values) (UNEP/SETAC, 2013)

  • Increase of wellbeing, using questionnaires/interviews (Ambrose et al., 2020)

For large commercial RTGs, an SLCA is better suited. This methodology aims to assess the social and socio-economic aspects of products along their life cycle. The SLCA guideline framework distinguishes five groups of stakeholders: workers, local community, society, consumers, and value chain actors. Next comes a second level including six impact categories: human rights, working conditions, health and safety, cultural heritage, governance, and socio-economic aspects, and then a third one including impact subcategories and social indicators (see figure below). SLCA studies usually target sector or company scales, or products produced in developing countries, with social conflicts or special interests.

Figure: Example of social indicators (Zamagni et al., 2015) (click to download)

Fig A.3 Example of social indicators (Zamagni et al., 2015).png