Experimental Design Details
With this study, I aim to investigate households’ WTP for programmable heating thermostats. In addition, I am interested in whether information on the potential cost savings for households or information on the potential emission reductions affects the WTP and whether this effect differs between the two types of information. Lastly, I also aim to study the role of the winning probability for the elicited WTP values. To this end, I designed a randomized, incentivized experiment with a lottery and integrate it in the questionnaire of the third survey wave of the GHHP.
Baseline data on household characteristics, demographic information, building characteristics, heating systems and energy efficiency of the building stem from the first, second or third survey wave of the GHHP, i.e. from 2021, 2022 or 2023. This information is usually only asked once, depending on the time participants enter into the GHHP. However, when participants move between two survey waves, they are asked to state their building characteristics again. Other information, like current energy cost, past and planned energy retrofit activities and socio-economic characteristics are asked to participants in each survey wave.
At the beginning of the experimental part, I first ask all respondents about their type of main thermostat that they use to control the heating temperature in the majority of their rooms. Here, households can for instance already state whether they own a programmable
thermostat. As all households, even households that have already installed programmable thermostats, will be asked about their WTP, this serves as an important control variable. Afterwards, all respondents will receive some basic background information about programmable heating thermostats to ensure that every respondent has some basic knowledge and understands what type of thermostat the subsequent questions refer to. In this short text, participants will learn that the thermostats can be installed on all heating radiators by taking off the old one and either directly or with help of an adapter installing the new one on the radiator. In addition, respondents will learn that programmable thermostats can measure the room temperature and control the radiator valve and thus the room temperature automatically. They will also learn that they can set heating profiles (directly at the thermostat or via an app) and that the thermostat can automatically detect ventilation times and that users can still manually change the heating temperature if needed. Households who have not installed any programmable thermostats yet will then be asked whether they have heard about programmable thermostats before. To elicit respondents’ prior level on informativeness, they will also be asked how well-informed they feel about heating thermostats. Afterwards, I require respondents to state their belief about energy cost changes and about their expectation regarding potential emission reductions, both induced by the installment of programmable thermostats. Subsequently, respondents will be informed that on the following survey pages, they have the chance to win a voucher or one programmable thermostat with the previously described characteristics. Here, respondents have the chance to opt out of this lottery.
Respondents who stay in the lottery will then be randomly divided into the six groups described in the intervention, whereas respondents who opt out will be randomly divided into three groups.
Each group receives specific information about programmable thermostats (see Intervention) and will subsequently be presented with a multiple price list (MPL) consisting of ten choices, each between a voucher of a certain euro value and a programmable heating thermostat. At the outset of the experiment, I explain to participants who did not opt out of the lottery that if they are randomly drawn as part of the lottery with the respective winning probability, one of their ten choices between a voucher or a programmable thermostat will be randomly chosen and actually paid out such that participants have an incentive to state their true WTP.