Healthy Buildings 2017 Europe July 2-5, 2017, Lublin, Poland. Improved perceived indoor environment in renovated and energyretrofitted

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1 Healthy Buildings 2017 Europe July 2-5, 2017, Lublin, Poland Paper ID 0030 ISBN: Improved perceived indoor environment in renovated and energyretrofitted social housing Henrik N. Knudsen Danish Building Research Institute, Aalborg University, Copenhagen, Denmark * Corresponding hnk@sbi.aau.dk SUMMARY The purpose of the present study was, among other things, to evaluate how tenants perceived the indoor environment in renovated and energy-retrofitted social housing erected in the 1960s. Tenants answered a questionnaire to quantify problems and satisfaction with the indoor environment before and after the renovation work. A majority of tenants perceived the indoor environment improved for all parameters: temperature, draught, air quality, noise and daylight, after the renovation work. In particular, the tenants experienced fewer problems with too low temperature and draught during the winter, noise from outside and too little daylight. The evaluation shows that it is possible to achieve a win-win situation, with both energy savings and improved perceived indoor environment. The evaluation also reveals that careful attention is needed to avoid introducing annoying noise from new technical installations. KEYWORDS Building renovation, energy savings, indoor climate, tenant s experience and satisfaction. 1 INTRODUCTION The need for renovation and energy savings in Danish residential buildings is massive, especially for the large number built in the 1960s and 1970s (Thomsen et al., 2012). The potential benefits of building renovation with a strong focus on reducing energy consumption are many (Almeida, M. et al., 2015). Better wall and roof insulation, low-energy windows and ventilation systems with heat recovery should lead not only to lower energy consumption, but also to benefits for the tenants in the form of better perceived indoor environment and comfort, among other things. Energy retrofitting in connection with renovation of existing buildings is a complex business, which can have adverse and unexpected effects if done incorrectly. This was experienced after the energy crises in the 1970s. At that time, it was relatively easy to achieve energy savings, and in the 1980s and 1990s a lot of energy-saving measures were carried out, mostly in the form of new windows, tightening of buildings and some extra insulation. Tightening of buildings, however, without establishing sufficient ventilation rates often caused a negative impact on the indoor environment, for example directly by an increased concentration of air pollutants and indirectly by mould growth and an increased number of house dust mites due to

2 a more humid dwelling (Batty et al., 1984). These negative experiences have fostered a fear of energy retrofitting among some lay people and professional stakeholders. Since the 2000s, the agenda of global climate change has once again put focus on low-energy buildings and energy retrofitting of existing buildings due to the large potential for reducing energy consumption and for reducing greenhouse gas emissions at the same time. Nonetheless, this new focus on energy retrofitting of buildings has heightened awareness among construction experts, building owners and energy authorities regarding the importance of not repeating the mistakes committed in the 1980s and 1990s in relation to energy retrofitting and negative impact on the indoor environment and comfort. Therefore, the requirements for both energy consumption and the indoor environment in new and existing buildings are getting more and more ambitious for every update of the Danish Building Regulations. A recent survey among house owners living in new low-energy singlefamily houses revealed a high general satisfaction where more than 90% perceived the indoor environment as satisfactory both in summer and winter (Knudsen et al., 2015a). The majority perceived the various indoor environment parameters to be better in their new low-energy house compared with conditions in their former house. Energy retrofitting in connection with renovation of existing buildings is typically much more complex than erecting new buildings. There are indications that point towards that if done correctly, there is an opportunity for a win-win situation, where energy is saved and the indoor environment is improved at the same time. This is achieved among other things by establishing adequate ventilation rates by mechanical ventilation and eliminating cold bridges by insulating the building envelope. The present study was conducted to expand the still insufficient knowledge in this field (Knudsen and Jensen, 2015). The objective of the present project was, among other things, to evaluate tenants experiences and satisfaction with the perceived indoor environment in renovated and energy-retrofitted social housing erected in the 1960s. 2 METHOD Tenants experiences and satisfaction with the perceived indoor environment was studied by means of questionnaire surveys in three Danish settlements belonging to the social housing sector; in terraced houses in Albertslund Syd located west of Copenhagen, in blocks of flats in Vapnagaard located in Elsinore north of Copenhagen and blocks of flats in Traneparken situated in the village of Hvalsø west of Copenhagen (Knudsen and Jensen, 2015; Knudsen et al, 2015b; Thomsen, 2016). All settlements are representative of the first large wave of prefabricated constructions built in the 1960s. The houses consist of 550 dwellings in Albertslund Syd, 1450 dwellings in Vapnagaard and 66 dwellings in Traneparken. The energy retrofitting was most ambitious and comprehensive in Albertslund Syd. Conditions of these houses were very poor and most worn-down before the renovation work, with no insulation under the floors, windows in poor condition, much building damage, for example leaking roofs, eroded facades, and pronounced mould-growth indoors. Due to the limited space of this paper, only the results from the comprehensive renovated settlement Albertslund Syd is presented. For further results, see the above references.

3 The renovation work and energy retrofit To remedy the above-mentioned problems and to reduce the energy consumption, these measures were taken in the settlement Albertslund Syd: Balanced ventilation system with energy recovery New end-wall facade with additional insulation New entrance facade with additional insulation New living-room facade with additional insulation Additional insulation of the roof Additional insulation of the floor against the basement New low-energy windows New bathroom New kitchen Renovation of green areas The renovation work and energy retrofit in Albertslund Syd resulted in a substantially reduced heat consumption of 61%. The questionnaire A questionnaire was developed to evaluate the tenants overall satisfaction with how the renovation work was carried out and more specifically their experiences and satisfaction with the renovation work. The latter included the perceived indoor environment (temperature, draught, air quality, noise and daylight) before and after the renovation work with an evaluation of problems with different aspects of the parameters and satisfaction with the parameters, followed by an evaluation of the indoor environment as a whole. Tenants had the possibility to supplement with additional personal comments. The tenants were briefly informed about the questionnaire survey at residents' meetings and it was also announced on the housing association s homepage. In February 2015, the questionnaire survey was conducted among 240 tenants in the terraced houses in Albertslund Syd. The survey was carried out by distributing a letter to each dwelling with a brief description of the project and an invitation to participate in the survey. The tenants accepted the invitation by filling in a questionnaire using an online survey system. To encourage tenants to complete the questionnaire, they were offered the opportunity to participate in a draw for gift certificates worth 93 (DKK 700). One week after distributing the letter, a poster was put up in the stairwells with a friendly reminder to those who had not yet responded. By the final deadline, a total of 56 tenants had answered, corresponding to a response rate of 23% in Albertslund Syd. 3 RESULTS Over half (63%) of the tenants found that the result of the renovation work lives up to their expectations. Questioned about whether they would recommend other housing associations to renovate their properties with focus on reducing energy consumption, 74% of the tenants supported this recommendation. This overall satisfaction shall be seen in relation to the fact that more than 70% of the tenants experienced some kind of inconvenience during the renovation process, including noise, dust and the presence of craftsmen. In spite of this, only 20% were overall dissatisfied with how the renovation work was carried out whereas 58% were satisfied. This may reflect the fact that the communication about the renovation process had ensured a matching of expectations among the tenants and housing association.

4 Perceived indoor environment problems In general, problems with various indoor environment aspects of the different parameters were reduced after the renovation works, see Figure 1. For example, the percentage of tenants who had problems with the temperature being too cold fell from 58% before to only 5% after the renovation work. The percentage of tenants who had no problems with the temperature conditions rose from 18% to 51%. Likewise, the percentage of tenants who had problems with noise from outside and too little daylight fell from 44% and 33% before to only 5% and 2% after the renovation work, respectively. As an exception, more (35%) tenants experienced problems with noise from technical installations (mainly the ventilation system according to comments) after the renovation work compared with only 9% before the renovation work. 90 Tenants having problems (%) Before Too hot Too cold Too varying temperature Stuffy air Unpleasant smells Noise from outside, e.g. traffic noise Noise from activities inside the building Noise from technical installations Too much daylight Too little daylight Glare from sun and sky After Temperature Air quality Noise Daylight Figure 1. The percentage of tenants who have problems with different aspects of the indoor environment parameters before and after renovation. Satisfaction with perceived indoor environment Figure 2 shows the frequency of tenants who are satisfied with the different indoor environment parameters temperature, draught, air quality, noise and daylight and the indoor environment as a whole before and after the renovation work. For all the parameters, the number of satisfied tenants increases markedly. For the perceived indoor environment as a whole, the number of tenants who are satisfied rose from 17% before to 91% after the renovation work. 4 DISCUSSION Despite comprehensive inconvenience during the month-long renovation process, the tenants expressed an overall satisfaction with how the renovation work was carried out and that the final result lived up to their expectations. The majority would recommend other housing organisations to renovate their properties.

5 Satisfied tenants (%) Temperature Draught Air quality Noise Daylight Indoor environment as a whole Before Figure 2. The percentage of tenants who are satisfied with the different indoor environment parameters and the indoor environment as a whole before and after the renovation work. Improved perceived indoor environment is part of this positive overall evaluation. Before the renovation work only a minority of the tenants were satisfied with the indoor environment, whereas the majority after the renovation work was satisfied with the indoor environment for all parameters (temperature, draught, air quality, noise and daylight) and the indoor environment as a whole. Before the renovation work, there were several perceived indoor environment problems related to the poor status of the building and its technical systems. Due to improved insulation of the buildings, new and better insulated windows and installation of a ventilation system with heat recovery, these problems have been reduced significantly. In particular, the number of tenants who experienced fewer problems with low temperatures during winter, discomfort from draught, noise from outside and too little daylight is notable. In addition, improvements were experienced regarding the perceived air quality, which can probably be attributed to the installation of ventilation systems which ensure a higher and more constant ventilation rate. One parameter stands out from this positive picture, namely noise from technical installations. Comments from the tenants indicated that this problem is mainly caused by noise from the newly installed ventilation system. This underlines the need for a holistic approach when renovating existing buildings, so that solving one problem does not introduce another problem. The results presented in this paper stem from the settlement which had been through the most comprehensive renovation of the three investigated settlements (Knudsen and Jensen, 2015; Knudsen et al, 2015b). The positive impact of the renovation work on the indoor environment has therefore, as could be expected, also been most pronounced. You might say that the renovation work has been so comprehensive that the final result is close to a newly erected building. The result of the evaluation is also close to being as positive as a recent evaluation among house owners living in new nearly-zero energy single-family houses (Knudsen et al., 2015a). That survey revealed a high general satisfaction and that more than 90% perceived the indoor environment as satisfactory both in summer and winter. The majority of the house owners perceived the various indoor climate parameters to be better in their new low-energy house compared with conditions in their former older house. After

6 All the above-mentioned evaluations of new low-energy buildings and energy retrofitted existing buildings show that it is possible to achieve a win-win situation, with both energy savings and improved perceived indoor environment. 5 CONCLUSIONS The overall conclusion is that it is possible to achieve a win-win situation, with both energy savings and an improved perceived indoor environment, as well as a number of other benefits, when implementing a comprehensive renovation in an older building stock with focus on energy savings. A majority of tenants perceived an indoor environment improved for all parameters: temperature, draught, air quality, noise and daylight, after the renovation work. In particular, the tenants experienced fewer problems with too low temperature and draught in winter, noise from outside and too little daylight. The evaluation also revealed a need for careful attention to avoid introducing annoying noise from new technical installations. These positive effects on the indoor environment, together with building improvements and energy savings, should, if communicated in the right way, help reduce barriers and motivate tenants and thereby help building organisations to initiate and implement major renovations and energy retrofits of their old building stock. 6 ACKNOWLEDGEMENT The project was made possible by the support of the Joint European Medical Research Board (JEMRB) and the Danish Energy Agency. The three administrations of the investigated social housing BO-VEST, Boliggaarden and Building Association Zealand have kindly been helping with the implementation of the project. All tenants who took time to answer the questionnaire are also gratefully acknowledged. 7 REFERENCES Almeida, M. et al Co-benefits of energy related building renovation - Co-benefits and demonstration of their impact on the assessment of energy related building renovation, International Energy Agency, Energy in Buildings and Communities Programme. Batty W. J., O Callaghan P. W. & Probert S. D Energy and condensation problems in buildings. Applied Energy, vol.17, pp Knudsen, H. N. & Jensen, O. M Tenants experiences and satisfaction with renovated and energy retrofitted social housing. (SBi; 28, Vol. 2015). Copenhagen: Danish Building Research Institute, Aalborg University, Knudsen, H. N., Mortensen, L. H. & Kragh, J. 2015a. Satisfaction with indoor climate in new Danish low-energy houses. Proceedings of 7th. Passivhus Norden conference 2015: Sustainable Cities and Buildings Knudsen, HN, Thomsen, KE, Rose, J & Bergsøe, NC. 2015b. Tenants' experiences and satisfaction in social housing subject to comprehensive retrofitting: A Danish case study. (SBi; 20, Vol. 2015). Copenhagen: Danish Building Research Institute, Aalborg University, Thomsen, K.E., Rose, J., Mørck, O., Jensen, S.Ø., Østergaard, I., Knudsen, H.N. & Bergsøe, N.C Energy consumption and indoor climate in a residential building before and after comprehensive energy retrofitting, Energy and Buildings, vol 123, nr. 2016, pp Thomsen, K. E., Knudsen, H. N., Mortensen, L. H., Aggerholm, S., Jensen, O. M. & Wittchen, K. B Task Force. Network for energy retrofit: Collection and presentation of existing knowledge about energy retrofitting of existing buildings, SBi; No. 09, Vol (In Danish). Copenhagen: Danish Building Research Institute, Aalborg University.