Henrik N. Knudsen 1, Ole M. Jensen 1, Lars Kristensen 2 Danish Building Research Institute, Aalborg University The green House/Energy Service Denmark

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1 Occupant satisfaction with new low-energy houses Henrik N. Knudsen 1, Ole M. Jensen 1, Lars Kristensen 2 Danish Building Research Institute, Aalborg University The green House/Energy Service Denmark SUMMARY The development and the erection of low-energy buildings have been intensified in recent years. Still, there are only few studies of the energy performance and occupant satisfaction with living in low-energy houses. A questionnaire survey was therefore carried out among occupants of low-energy houses. The purpose was to study occupant satisfaction with new low-energy houses concerning i.a. the perceived indoor climate and the technical installations for heating and ventilation. The survey showed an overall satisfaction with the new lowenergy houses, but also that there were problems that should be addressed to make low-energy houses more attractive to ordinary people. Problems could be that it was too hot in summer and too cold in winter; that there were initial difficulties with the technical installations and that they were difficult to use. A series of recommendations to increase occupant satisfaction in existing and future low-energy houses are given. KEYWORDS Energy performance, indoor environment, indoor climate, questionnaire survey, regulation. 1 INTRODUCTION The Danish municipality of Køge south of Copenhagen initiated the settlement Fremtidens Parcelhuse (Detached Houses of the future), a pilot project in a new area for urban development. The settlement should meet the low-energy requirements as defined in the Danish Building Regulations Thus, houses should be designed and constructed to have an energy consumption that was at least 25% lower than the requirement, i.e. an on-site primary energy consumption of 52.5 kwh/m 2 /year kwh/year divided by the (gross) heated floor area. This includes energy for hot water, electricity for building operation (multiplied by a factor 2.5 to convert to primary energy), local renewable energy production and a possible penalty for overheating. For a standard family living in a detached house of 150 m 2, this gives a maximum primary energy consumption for space heating of 44 kwh/m 2. The above low-energy requirements are now minimum requirements of the current Danish Building Regulations Another requirement to the settlement was that the houses should qualify for the Nordic Swan eco-label. This requires among other things: 1) a clear manual for the heating and ventilation systems that shows how to operate the systems to achieve the optimal energy efficiency and indoor climate and 2) instructions on how to maintain a good indoor climate. Nearly all houses were equipped with a heat pump and a ventilation system with heat recovery. The first houses were occupied in This paper presents part of the results of an evaluation of the pilot project that was performed in the settlement (Kristensen et al. 2010). The evaluation consisted of a questionnaire survey of occupant satisfaction in all houses, and a series of physical measurements in selected houses. This paper focuses on the questionnaire survey, the objective of which was to study the occupants satisfaction with their new low-energy houses concerning i.a. the perceived indoor climate and the technical installations for heating and ventilation.

2 2 METHODS The questionnaire survey was conducted in May 2010 when the occupants had been living in their houses for a period ranging from 4 to 36 months. It was carried out by sending letters by regular mail with a brief description of the project and an invitation to participate in the study by filling in a questionnaire by using an online survey system (SurveyXact). All registered adults (77) in occupied houses (40), were asked to participate. A reminder was sent out 10 days after the first invitation. Respondents were informed that they would get a gift certificate of 13 euros if they participated in the survey. The questionnaire was answered by 48 occupants corresponding to a response rate of 62.3%. Women constituted 56.2% (27) of the respondents. Responses (1 or more) were received from 28 out of the 40 homes corresponding to a response rate of 70.0%. The questionnaire survey focused on the occupants overall satisfaction with their new low-energy houses; perceived indoor climate summer and winter; technical installations; regulation of the indoor climate summer and winter; practice of opening windows; availability and quality of information and heat consumption. 3 RESULTS AND DISCUSSION A high response rate was achieved. This may be due to the occupants involvement and the fact that every participant would receive a gift certificate as a reward. Occupants overall satisfaction Occupants were generally satisfied with their new houses. To the broad question Can you recommend others to live in a low-energy house?, 85% answered yes and 15% maybe. There was also a high degree of satisfaction with the interior design of the houses, which they themselves had been involved in arranging. On the question "Does the interior design of your home in general meet your needs?", the occupants gave an average score of 4.4 (the highest score) on a 5-point scale from "No, not at all" (1) to "Yes, definitely" (5). As many as 56% answered "Yes, definitely" (5). The occupants were also more satisfied with the temperature conditions and air quality in their new house compared with their earlier house, see below. Perceived indoor climate summer and winter To the broad question "Are there situations or times when you are not satisfied with the indoor climate in your home?", 44% answered yes. The main reasons for the dissatisfaction were that it was either too warm or too cold and a few occupants had odour problems. The occupants were asked about the perceived indoor climate last summer and winter concerning the five parameters temperature, air movements, air quality, noise and daylight on a 5-point scale ranging from Unsatisfactory (1) to Satisfactory (5). One question was, for example, What do you think about the indoor climate in your house, regarding the temperature last summer?. Table 1 shows the mean values for the five parameters and a general assessment of the indoor climate last summer and last winter. During the summer the mean values of assessments of satisfaction on the 5-point scale varied from 3.3 (temperature) to 4.4 (daylight). The mean value of the assessments of the 5 parameters and the general assessment of indoor climate last summer was 3.8. This meant that the occupants were most dissatisfied with the temperature conditions and most satisfied with the daylight conditions. A majority (68%) of the occupants specified that they experienced that it was too warm during summer. This was the most prevalent complaint, and in

3 Table 1. Mean values of assessments on a 5-point scale 1 of satisfaction with five indoor climate parameters and a general assessment of the indoor climate last summer and last winter Parameter Summer Winter Temperature Air movements Air quality Noise Daylight General assessment of the indoor climate point scale ranging from Unsatisfactory (1) to Satisfactory (5) agreement with physical measurements and calculations in Fremtidens parcelhuse and other low-energy houses (Kristensen, 2010; Vagiannis, 2012; Larsen, 2011). Despite the general satisfaction with daylight conditions, up to 33% (16) indicated that they wanted more or less light in some rooms, e.g. 27% (13) would like less light in the bedroom and 23% (11) would like to have less light in the living room. During winter the mean values of assessments of satisfaction on the 5-point scale varied from 3.5 (temperature) to 4.4 (daylight). The mean value of the assessments of the 5 parameters was 3.9 and the mean value for the general assessment of indoor climate was 3.6. This meant that during winter the occupants were most dissatisfied with temperature conditions and most satisfied with daylight conditions. Of respondents 27% (13) specified that they experienced that it was too cold, and 25% (12) found that the temperature varied too much. Some respondents explained that problems with temperature conditions were related to various technical problems, see below. Moreover, 25% (12) of the respondents indicated that they experienced problems with draught. The occupants generally expressed satisfaction with the daylight conditions and only 15% (7) of respondents indicated that they experienced problems with too little daylight, glare from sun and sky or something else. Only approx. 17% (about 8) expressed that they would prefer to have more or less light in some rooms. It is worth noting that around one third of the respondents (16/17) experienced problems with noise from the technical installations over the year. Thus, some occupants experienced problems with the indoor climate. To put these problems in perspective, a comparison with the occupants previous house was made by asking "How do you experience the temperature conditions in your new home compared with your former home?" and similar for air quality. A majority of the occupants responded positively that the temperature conditions (69 %) and air quality (85 %) were better in their new house. To raise occupant satisfaction where there were problems with the indoor climate, more comfortable conditions of temperature should be provided, i.e. less warm conditions in summer, warmer conditions in winter and a more stable temperature. Possible energy-efficient solutions could be external solar shading where it had not been established yet, smaller windows facing the sun, having a strategy related to the practices of ventilating by opening and closing windows (natural ventilation) and a faster temperature regulation with sufficient heat capacity in all rooms. More silent installations would also be desirable. Technical installations There were a series of initial problems with the technical installations. Occupants experienced problems with technical installations in summer (60%) and winter (67%). About one third of

4 the respondents experienced problems with noise from technical installations, problems with solar shading and problems with heating and ventilations systems. Low-energy houses are relatively advanced, with several more or less complicated technical installations like for example a ventilation system, a heating system, a heat pump, photovoltaic and solar heating. This resulted in a number of critical comments from the occupants such as The system is so complex that it's hard to remember what to do for proper operation of installations and The manual is intended for engineering nerds not to mention the most critical comments that it would be inappropriate to put in print. These relatively complicated installations usually had different user interfaces, which did not necessarily apply the same logic, terminology and symbols. There is a risk that a system is so advanced that it can be difficult to use and to achieve an optimal interplay between the different installations. This can lead to energy consumption not being as low and indoor climate not being as good as it was intended. In some houses it was apparently forgotten that occupants feel more satisfied with the indoor climate if they can control it, e.g. by adjusting the temperature, the ventilation or the use of solar shading. Thus, more user friendly and robust installations are needed. To achieve this, it is recommended to involve occupants in innovative product development. A higher degree of satisfaction could also be achieved by an improved transfer process, where the technical installations run as intended from day one, combined with better follow up on acute problems. Regulation of the indoor climate summer and winter To the broad question "Are there typical situations or moments where you are not satisfied with the automatic regulation of indoor climate in your home?", 52% of the occupants answered yes. Some specified that they were dissatisfied due to a slow temperature regulation. On another broad question "Are there typical situations or moments when you are not satisfied with your personal regulation options?", 48% of respondents answered yes. Some specified that they were not satisfied with the slow temperature regulation, and that it was difficult/complicated to regulate the temperature and that they would like to have solar shading. The dissatisfaction was in some cases related to a floor heating system that reacted relatively slowly. Occupants were asked three questions (Q1, Q2 and Q3) for a more detailed assessment of their experience with the regulation of ambient temperature, ventilation and solar shading over the year, see Table 2. Table 2. Mean values of assessments on 5-point scales of experience with the regulation of room temperature, ventilation and solar shading Question Room temperature Ventilation Solar shading Q1 To what extent do you feel that you personally have the ability to regulate and adjust the following? 1 Q2 Do you feel that you need to be able to regulate the following? Q3 If you have the opportunity, how fast is there a change of the indoor environment if you regulate the following? point scale from "No possibility to personally regulate" (1) to "Full personal ability to regulate" (5) 2 5-point scale from "No, never" (1) to "Yes, very often" (5) 3 5-point scale from "Very slowly" (1) to "Very quickly" (5)

5 For Q1, there were answers at all 5 levels on the 5-point scale for all 3 parameters, which expressed a big variation in occupant s perceived ability to regulate and adjust the parameters. The highest number (29%) answering "No possibility to personally regulate" (1) was for sun protection, reflecting that not all houses had mounted an exterior solar shading and it should be expected that not everyone had solved the problem with interior solar shading. For Q2, there were also answers at all 5 levels for all 3 parameters, which expressed a big variation in the occupants perceived need to regulate the parameters. For Q3 and room temperature, only one (2%) occupant felt that it was "very fast", while 9 (19%) found that it was "very slowly". Compared with the other two parameters, the regulation of room temperature was perceived as being slow. Among the 38 occupants (79%) who were able to regulate solar shading, the majority found it to be quick. The ventilation was also found to react quickly for just over half of the occupants. Practice of opening windows Occupants were asked about their practice with respect to opening windows day and night in summer and winter with the questions "Do you or others in the household, from time to time, open the windows during the day/night?". In the summer situation, 92% answered yes during the day and 56% during the night. It was justified by a desire to get fresh air and because it was (too) warm. In the winter situation, 75% answered yes during the day and 17% during the night. It was also justified by a desire to get fresh air and to a limited extent because it was (too) warm. It is noteworthy that it was so relatively common to open windows to get fresh air even when the great majority of the houses had mechanical ventilation. This practice could increase the comfort or be a practice learned during childhood or a practice relevant in a former home. In any case, it has consequences for the energy consumption during the heating season. Availability and quality of information Qualifying for the Nordic Swan eco-label requires i.a.: 1) a clear manual for the heating and ventilation systems that shows how to operate the systems to achieve optimum energy efficiency and indoor climate and 2) instructions on how to maintain a good indoor climate. There were problems with this information with respect to both availability and quality. Generally, there was a lack of useful information from the suppliers of the houses, as between 19 and 50% did not receive the promised information. Of those who received information, between 27 and 37% found the information unsatisfactory. Maybe as a consequence, half of all occupants stated that they were unable to use the possibilities of their home optimally. There is a need for an informative and easy-to-understand user manual or online support as well as an improved commissioning process and follow-up, which would allow the occupants to be able to use their house from day one as intended. Heat consumption The occupants experienced that the energy consumption was higher than expected. Of the occupants, 50% answered no to the question Is your heat consumption as low as you expected?. According to the occupants, it was not because of high indoor temperatures. Several families reported that they kept a lower temperature (in average 19 C) in the bedroom than in other rooms (in average 22 C). A review of comments made about the energy consumption showed that many occupants were surprised at how high it was and that it was higher than expected and higher than promised. The big differences and the shattered expectations could to some extent be explained by different behaviour, e.g. bathing habits of families varied between 3 and 36 showers a week.

6 The observed primary energy consumption in the nine selected houses adjusted for degree days, indoor temperature and residents' consumption of hot water was higher than predicted at the design stage. On average, it was 31% above the calculated energy frame and 13% above the requirement of the current Danish Building Regulations However, a wide variation was observed as one house consumed twice as much energy as calculated, whereas another house had a normalised energy consumption that was only two thirds of the calculated one. The behaviour of building users is not always rational in relation to energy consumption and indoor climate. This is due to many factors, but if more knowledge and information were available to users about how a particular behaviour affects energy consumption and indoor climate, this might influence user behaviour in a positive direction. This knowledge could to some extent be contained in the technical installations and be made available as feedback to occupants through a user interface. 5 CONCLUSIONS There was overall satisfaction with the new low-energy houses, but there are challenges that need to be addressed to make low-energy houses more attractive to ordinary people. Occupants experienced that it was too hot in summer and too cold in winter, that there were a series of problems with the technical installations and that their use was difficult and the energy consumption was higher than expected. A series of recommendations to increase occupant satisfaction in present and future lowenergy houses can be given: 1) Avoid uncomfortably high temperatures during summer by some a kind of external solar shading, consider the size of the windows facing towards the sun and make effective use of natural ventilation possible. 2) Develop more robust and easy-touse technical installations enabling ordinary occupants to control the indoor climate and energy consumption as intended in their new relatively technically advanced house, e.g. by a single user-friendly user interface that can communicate with all relevant technical installations. 3) Provide good information and communication on how to operate the technical installations, e.g. in the form of an informative and easy-to-understand user manual and/or support on the internet. 4) Ensure that occupants can use their house as intended by technical installations being fully operational from day one. 5) Communicate about the houses energy consumption so that occupants get realistic expectations according to their family situation and behaviour. ACKNOWLEDGEMENT The study was supported by the Danish Energy Agency through an EFP-07 project Erfaringsopfølgning på lavenergibyggeri klasse 1 og 2: - med "Fremtidens Parcelhuse" som eksempel, contract # ENS All occupants who took time to answer the questionnaire are gratefully acknowledged. 6 REFERENCES Kristensen, L., Jensen, O. M., Knudsen, H. N., Rasmussen, T. V., Bergsøe, N. C., Kragh, J., Arvedsen, H. & Olsen, T. Erfaringsopfølgning på lavenergibyggeri klasse 1 og 2: - med "Fremtidens Parcelhuse" som eksempel, 2010 Det Grønne Hus. 197 p. (In Danish). Larsen, T. S. (2011). Overheating and insufficient heating problems in low energy houses up to now call for improvements in future. REHVA Journal, 48(3), SurveyXact Vagiannis, G., Knudsen, H.N., Toftum, J. and Clausen, G Simulation of indoor environment in low energy housing, Proceedings of Healthy Buildings 2012.