International Energy Agency Energy Conservation in Buildings and Community Systems Occupants experiences in dwellings with different LT heating systems Silvester, Sacha de Vries Ger and Op t Veld, Peter. 2. Internal report of IEA ECBCS Annex 37.
Contents 2-4-4 Chapter Title Page 1. Introduction 3 2. Background information occupants and provisions 5 3. Evaluation LT-systems 4. Summary and conclusions 17 2
2-4-4 1. Introduction One of the critical success factors for a broad implementation of Low Temperature Heating systems in residential buildings is the acceptation by the occupants. At this moment the costs for LT heating systems for dwellings are higher then the traditional HT systems while energy savings are in some cases marginal. This means that LT systems also must have some additional qualitative benefits for occupants (thermal comfort, indoor air quality, safety, etc.). The overall performances of LT heating systems must be at least equal or preferably better then traditional HT systems. Important questions are: Are the extra costs for the occupants acceptable, are they willing to pay an extra price for these systems? What do occupants see as advantages and as disadvantages? How do they use these systems? The first objective of the occupant survey was to make an inventory of the experiences of occupants with LT systems and to look if these systems fulfil the expectations of occupants. These results can also give insight in possible barriers for a further market introduction. This occupants survey for LT systems is carried out in the framework of the Dutch implementation programme for LT systems. For this survey nine projects have been selected The most important selection criteria are: Projects must have more then 2 dwellings; Dwellings must have been inhabited for at least one full year. Next table gives an overview of the selected projects with brief descriptions. Project name Description Number of Tilburg: Apartments, LT-radiators, Mechanical Ventilation 72 Cenakel Heat Recovery, central heating system with Wijk bij Duurstede: De Geer Winterswijk: Homansbos en Pottenbakker Den Haag: Weerselostraat Nieuwegein: Galecop Harderwijk: Drielanden condensing boiler Semi-detached, LT-radiators, mechanical extract, Integrated solar boiler for heating and DHW Semi-detached, LT-radiators, mechanical ventilation, Solar boiler for heating and DHW and sunspace Apartements, LT-radiators, Mechanical Ventilation Heat Recovery, Integrated solar boiler for heating and DHW (58)/ solar boiler-condensing boiler combination (6) Terraced, floor heating 1st floor, LT-radiators 2nd floor, mechanical extract, central DHW, central heat pump Terraced, LT-radiators, Mechanical Ventilation Heat Recovery, LT-district heating and central DHW, PVcels, sunspace Terraced, LT-radiators, Mechanical extract, central DHW, mini cogeneration plant combined with heat pump 28 8 64 72 67 13 3
Maastricht: Amby-Zuid / Amboise Boven- Leeuwen: Zonnewoud Hooglanderveen : Beeklaan Table 1 Selected projects Semi detached, wall heating, mechanical extract ventilation, DHW with solar boiler, heating with condensing boiler Semi detached, LT-radiators, mechanical extract ventilation, combined with heat pump for DHW, heating with condensing boiler Terraced, semi detached, detached, floor heating, mechanical extract ventilation, individual heat pump for heating and DHW, PV-cells Terraced, semi detached, detached, wall heating, mechanical extract ventilation, condensing boiler for heating and DHW Total 9 All 9 households have been contacted by October 1999 to co-operate with the questionnaires. These questionnaires contained questions about: Previous dwelling and situation, Social-demographic aspects, attitude to energy and the environment, the use in practice of the heating system the use in practice of the DHW system the use in practice of the ventilation system appreciation of the information contentment with dwelling and building services in general contentment with specific installation components valuation of indoor environment suggestions for improvements 9 9 42 25 2-4-4 Next figure shows the response per project: 55 5 45 35 25 2 15 5 Figure 1 Response per project 4
2. Background information occupants and provisions 2-4-4 Heating system previous dwelling The majority of the occupants did not have any experience with LT heating systems before. Most of the previous dwellings (77 for floor heating to 94 for wall heating) had central heating systems with HT radiators (the most common system in the Netherlands). Six percent of the households had floor heating in their previous home. 9 8 7 5 2 radiators local heating air heating floor heating Figure 2 Heating system previous dwelling versus current heating system Selection of dwelling in relation to LT heating Similar surveys (demonstration projects sustainable buildings) show that homes are not selected by occupants because of environmental reasons alone. However, for 58 of the households the environmental aspects of the home contributed in the final selection. This corresponds with the scores from other similar projects. Notable is the score for house holds with LT radiators: for 65 environmental aspects and measures were important in their decision for the selection of their home. The presence of wall heating was for 35 an important aspect for the selection. For floor heating this was even 71. Also notable was that if environmental aspects were considered in relation to the presence of LT heating systems, floor heating systems were considered to give a positive contribution to the dwelling but were not considered as an environmental or energy saving measure. Social-demographic aspects In this survey a number of social-demographic data have been collected. The objectives were to be able to estimate if specific groups of occupants could be discriminated and if this could be off any influence of the results or could give an eventual explanation for results. Only the project in Winterswijk differs from the other projects (number of inhabitants, net income, education) as this is a project for housing of elderly people. 5
Table 2 Family size 2-4-4 Family size is relative small in Tilburg, Winterswijk, Maastricht, Boven-Leeuwen and relative big in Wijk bij Duurstede and Den Haag. Table 3 Family income Net familiy income per month HFL Tilburg Wijk bij Duurstede Den Haag Maastricht Number of persons Tilburg Wijk bij Duurstede Winterswijk Den Haag Nieuwegein Harderwijk Maastricht Boven- Leeuwarden Hooglanderveen 1 26 6 55 8 12 8 2 59 6 45 11 28 25 8 72 42 3 15 23 25 5 4 25 4 65 41 28 25 2 12 25 >4 18 11 Winterswijk Nieuwegein Harderwijk Boven- Leeuwarden Family income is a little above average. Family incomes in Wijk bij Duurstede and Den Haag are relatively high. Table 4 Level of education Hooglanderveen <2 3 33 2-9 45 6 4-12 18 22 6 19 33 25 27 2-2 36 44 33 67 5 41 5 >5 56 46 44 44 25 32 Level of education Tilburg Wijk bij Duurstede Winterswijk Den Haag Nieuwegein Harderwijk Maastricht Boven- Leeuwarden Hooglander -veen Elementary 46 8 5 Lower 22 24 27 31 17 25 9 Secundary Higher 11 9 4 6 25 18 Secundary Lower 13 35 18 35 33 75 5 25 18 Vocational Higher 46 41 15 14 25 38 46 Vocational University 8 7 25 12 9 Higher levels of education appear in Boven-Leeuwen, Hooglanderveen and Tilburg. Lower levels of education appear in Winterwijk en Den Haag. Analysing the social-demographic aspects it appears that there are no significant differences within the group with floor and wall heating. The group with LT radiators exist if relative small families, lower incomes and lower levels of education. Attitude to energy and the environment The general attitude of occupants to energy and the environment is determined by asking the respondents the extent of agreement to number of propositions. The results are split up in type of heating. The results show that there is no significant difference between the three different groups. 6
2-4-4 I want to pay HFL per month extra for the environment 7 5 2 agree disagree How serious is current energy use as a threat for the environment 8 7 5 2 very serious serious not serious 9 8 7 5 2 I have contributed to the solution of envrionmental problems by living in a sustainable house. Now it'sother peoples turn! agree disagree Energy saving only make sense if everybody joins! 7 5 2 agree +/- +/- +/- disagree 7
2-4-4 How important is the environment for setting the thermostat for heating? 8 7 5 2 important +/- unimportant How important is thermal comfort for setting the thermostat for heating? 9 8 7 5 2 important +/- unimportant How important is energy saving for setting the thermostat for heating? 8 7 5 2 important +/- unimportant Use of dwelling and provisions Set point heating Occupants were asked about the set points of the thermostats for a winter evening and a winter night. Objective of this question is to get an impression of the use of the different LT systems. 8
2-4-4 winter evening T-average ( C) Floor 19.9 Wall 2.294 n.s. Radiator 2.2 s. n.s. For a winter evening the set point temperature for floor heating is significant lower (.7 ) then for radiators. winter night T-average ( C) Floor 17.816 Wall 17.588 n.s. Radiator 15.12 s. s. For a winter night the difference in set points for radiators on one hand and wall and floor heating on the other hand is significant. Heating of bedrooms 5 of the households do not use heating at all in bedrooms during winter. For dwellings with floor heating it more bedrooms are heated (in case if bedrooms are heated. No explanation could be found for this. Airing of bedrooms As in most Dutch houses airing provisions are used during wintertime during longer time. Notable is that in dwellings with wall heating in 47 of the cases airing provisions are used during several hours. In Hooglanderveen (all dwelling equipped with wall heating) 58 of the households use these provisions for six hours a day. A possibility is that the slowness of the system or the poor(er) controllability is a reason for occupants to control temperature by opening windows. However, no evidence is found in this survey. Project Boven-Leeuwen is equipped with floor heating on both floors. However, this project does not show significant difference in airing compared to projects with LT radiators. Use of sun spaces In projects Wijk bij Duurstede and Nieuwegein 42 dwellings have sun spaces. Although these sun spaces (can) have an energy reducing function, 19 of the households occasionally heat the sun space in winter time. More over, 14 the sun space is added to the living room. Although in general everybody is very satisfied, 98 of the households remarks that the sun space is too warm during summertime. Temperature level DHW 29 of the households have a set point lower then C (critical for Legionella). Relative many respondents with houses with floor heating (23) indicate that they have sent point temperatures for DHW lower then 55 C. 9
3. Evaluation LT-systems 2-4-4 Failures heating systems The occupants were asked about the overall functioning of their heating system. Many households (44) had failures with their heating systems during the first months of habitation of their new home. The occupants themselves could not repair these failures. Notable is that the most common system (LT radiators had the highest percentage of failures (48). Wall heating had the lowest score with 23. Information For 64 of the respondents the information about energy and environmental aspects of their home was sufficient. However, the information was clearer for wall heating (79) and floor heating (73) then for LT radiators (). The combination floor heating with heat pumps raised may unanswered questions by the occupants. These questions concerned a.o. the exact working of the system, the advantages and disadvantages of the system, and the costs for heating (structure of charges). Also more in general additional information was desired about the innovations, maintenance on longer term and guidelines about how to use this system as efficient as possible. Floor heating Two out of nine projects have floor heating (Den Haag en Boven-Leeuwen). In total, data of 52 dwellings are available. Floor heating was a major decision criterion for the selection of the dwelling as indicated by 71 of the households. As advantages of floor heating are mentioned: constant, equal, pleasant heat, temperature, and comfort (n=26) 5 no cold feet (n=16) 31 no radiators (n=12) 23 healthier, less dust and particles (n=3) 6 no dry air (n=2) 4 As disadvantages of floor heating are mentioned: slow heating up of the dwelling, sometimes too cold, sometimes too hot (n=18) 35 limitation of selection of floor covering (no wood, laminate) (n=8) 15 many failures during first year (n=4) 8 no temperature control possibilities per room (n=2) 4 no (visible) radiation source (n=2) 4 only limited night set back possible (n=1) 2 to dry (n=1) 2 high energy use (n=1) 2 The appreciation of the floor heating in project Den Hag en Boven-Leeuwen is more influenced by problems with the heat source then by actual problems with the emission system. Occupants were also unsatisfied about the promises of utilities about the low energy consumption of heat pumps (during the first year).
2-4-4 Occupants were asked about suggestions for improvements of the systems. Most of them marked that some measures about the disadvantages had to be taken, without saying what kind of measures. Following suggestions were mentioned: Adding an extra radiator; More information about the use and set points Better control/user-interface (per room, time controlled thermostat) Better tuning between floor heating and heat pump. Wall heating In Maastricht en Hooglanderveen wall heating systems were applied as main heating system In total, data of 17 dwellings are available. 35 of the households indicated that wall heating was a major decision criterion for the selection of the As advantages of wall heating are mentioned: no space needed for radiators (n=8) 47 cleaner air (n=6) 35 equal heat (n=6) 35 no cold draft (n=2) 12 low energy use (n=1) 6 no dry air (n=1) 6 no noise (n=1) 6 better indoor climate (n=1) 6 As disadvantages of wall heating are mentioned: slow heating up of the dwelling (n=7) 41 cold draft near windows with on places without tubes in wall (n=2) 12 limitations of drilling in walls (n=1) 6 no temperature control possibilities per room (n=1) 6 no central point to warm up (n=1) 6 Also for wall heating some households suggest to add an extra radiator to compensate the slowness of the system. Also controllability for each room was mentioned as a possible improvement. Another disadvantage is the limitation of drilling in walls. Some occupants want to have easy detection devices for the tubes. Another mentioned option for improvement is a combination of wall heating with floor heating. LT-radiators Most of the selected projects have LT radiators. This group is in this survey with 113 households over represented. 11
As advantages of LT-radiators are mentioned: no idea that LT radiators are different from HT radiators (n=35) 31 lower energy use (n=22) 19 less burning of dust, less smell (n=8) 7 equal heat (n=5) 4 pleasant heat/better radiation (n=3) 3 less dust in the air (n=2) 2 no dirt on radiators (n=1) 1 fast heating up (n=1) 1 2-4-4 As disadvantages of LT-radiators are mentioned: no disadvantages (n=) 35 more space needed (n=31) 27 radiators don t get really warm (n=8) 7 ugly design (n=6) 5 difficult to control (per room) (n=6) 5 (no thermostatic radiator valves) (n=4) 3 slower heating up (n=4) 3 badly installed/situated (n=2) 2 much dust (n=2) 2 noise (n=1) 1 Suggestions for improvement: Also for LT radiators controllability is mentioned as an aspect for improvement, i.e, per room and clock thermostat. Lack of information about the most efficient way of heating. Development of smaller radiators with special attention for design. Appreciation heat The radiant temperature as well as the air temperature influence thermal comfort. However it is difficult to translate the difference between air and radiant temperature to a level of appreciation. Occupants were asked to give their appreciation of the heat in a scale from very pleasant to very unpleasant. Floor heating scored a little better then wall heating. Relatively more occupant judged LT radiators as quite pleasant or unpleasant. Do you think that LT system gives pleasant or unpleasant heat? 8 7 5 2 pleasant quite pleasant unpleasant 12
Appreciation indoor environment 2-4-4 Cold draft near windows Wall and floor heating have a higher risk on discomfort near cold windows (cold draft). This risk is confirmed by the results of this survey. Households with LT radiators have less problems with cold during frost draft then households with floor and wall heating. Especially in households with wall heating 41 cases had problems with cold draft near windows in the living room during frost. Do you have problems with cold draft or draft near windows during frost? 9 8 7 5 2 Dust in the air yes no Influence of LT system on dust in the air 9 8 7 5 2 improved equal worsened Occupants were asked to compare indoor air quality in their current dwelling with their previous dwelling in relation to dust in the air. Notable is the response of occupants with dwellings with wall heating: 88 indicate that indoor air quality in relation to dust had improved. For the other dwellings (floor heating and LT radiators) no significant change was noted. Controllability heating systems Floor and wall heating are often connected with systems with a slow reaction time. However modern systems seem to react much faster. For this reason occupants were asked about their experiences with the heating up time after a longer period of absence The majority of the occupants with floor heating (55) and wall heating (65) indicate that the heating system does not heat up the dwelling very fast. 68 of the occupants with LT radiators indicate a fast heating up time. 13
2-4-4 Dwelling heats up fast after long period of absence 7 5 2 agree disaree However, these scores don t seem to have an influence on the satisfaction considering the controllability of the temperature. A minority indicates to be dissatisfied with the controllability of their heating system with no significant difference between floor heating () and wall heating (12) and a little better score for LT radiators (5). Satisfaction controllability temperature 7 5 2 satisfied +/- +/- unsatisfied Evaluation indoor climate Do you think that LT system gives an impovement of the indoor climate or not? 8 7 5 2 improved equal worsened Occupants were asked their opinion about the indoor climate in terms whether or not it was improved in relation to their previous dwelling. Notable, again, was the very positive score for floor and wall heating (>7). 61 of the occupants with LT radiators did not notice any difference. The results for wall heating don t differ from previous occupants surveys (demonstration projects sustainable building Silvester & de Vries). 14
Satisfaction with different LT-systems In next table the satisfaction of the occupants with their LT heating systems is given. Occupants with LT-radiators are less satisfied with their system then the other two systems. Results concerning satisfaction of wall heating and floor heating don t show significant differences; 7 of the occupants is satisfied about their system. The evaluation of the LT heating emission system and the total heating system (including heating source) are very much related. 2-4-4 Satisfaction with LT heating system/heating in general 9 8 7 5 2 satisfied (LT) +/- (LT) unsatisfied (LT) satisfied (heating) +/- (heating) unsatisfied Relation between evaluation heating with evaluation DHW system and ventilation system. The assessment of different provisions in a dwelling can be strongly influenced by the bad functioning of only one the systems. Also a very positive appreciation of one of the provisions can also mask other problems. For this reason the relation is studied and analysed between the heating system, DHW system and ventilation system. This evaluation show that the assessment of the DHW system is not related to the assessment of the heating or the ventilation system. The assessment of the ventilation system is however correlated to the heating system. Occupants who are satisfied about the function of the heating system are also satisfied about their ventilation system visa versa. Evaluation energy use The first objective of the implementation of LT systems in dwellings is to make the application possible of low valued, sustainable heat sources, now and in the (near) future. The second objective is that combination of Lt heating systems in combination with almost all heat sources lead to direct energy saving. It is interesting to know if occupants appreciate the possible energy savings. Evaluation electricity consumption 8 7 5 2 high normal low 15
2-4-4 Results of floor heating show a great difference with the other systems. This is caused by the fact that in two of the project with floor heating electrical heat pumps were installed. The electricity use was considerably higher then the calculations and predictions of the utilities. Evaluation gas ccnsumption 9 8 7 5 2 high normal low Evaluation of the gas consumption show a different picture in relation to electricity use. For floor heating and LT radiators a majority of the occupants indicates that gas consumption is lower then average. For floor heating only 8 dwellings had gas fired boilers; these households indicate that their gas consumption is normal. 16
2-4-4 4. Summary and conclusions Results of this survey can not be generalised for the total Dutch new build housing. All these projects concern demonstration projects for LT systems. There are reasons to assume that the households were aware that their dwellings were a part of a demonstration project. Except for the project in Winterswijk (elderly housing) the composition of the population is comparable with average new build dwellings. Also considering the attitude to energy and the environment no significant differences with other housing projects were noticed. The social-demographic aspects of households in projects with floor and wall heating showed no significant differences. The group of households with LT-radiators showed more households with low incomes and lower levels of education. Occupants did not select their dwellings because of environmental reasons or environmental, sustainable measures. For 58 the environmental measures were an important aspect for the final selection of their dwelling. Floor heating is an important decision factor for the selection but not as a particular energy or environmental measure. Therefor it is recommended to give more information and to communicate about the energy efficiency of LT systems. A majority of the respondents with LT-radiators don t have any idea that they have a LTsystems. On one hand positive because there seems to be no difference (disadvantage) in comparison with more conventional systems, on the other hand it could be recommended to communicate about the energy efficiency of these systems. There is significant difference between the set points of the thermostats between the different LT systems during winter nights. Occupants with floor and wall heating apply a small temperature difference for night set back. Also in cases of airing these occupants don t use a set back of thermostat temperature. Occupants ask for instructions how to use their heating provisions to reach an optimum between energy use and thermal comfort. About 5 of the occupants do not use heating in bedrooms during wintertime. Controllability of the heating system could be improved especially with floor and wall heating; to of the occupants mention poor controllability as a disadvantage. 17
2-4-4 This survey gives a good indication of the specific advantages and disadvantages of each system: LT-system Advantage Disadvantage Floor heating No radiators Equal distribution of heat Thermal comfort No cold feet Wall heating LT-radiators No radiators Equal distribution of heat Thermal comfort Slow heating up Limitation selection of floor covering Slow heating up Much space needed for radiators The advantages and disadvantages, mentioned by the occupants in this survey are matching the results of previous researches. This survey also confirms the results of the literature review on side effects of low exergy emission systems (IEA Annex 37 report). Especially the reaction of the occupants about the perception of indoor air quality, thermal comfort, slowness and controllability of some LT-systems confirm previous studies. Although LT-system are very well accepted and appreciated, especially floor and wall heating, some negative aspects and disadvantages could be taken into account and be solved. This concerns the controllability per room (floor and wall heating) and sizes, design and installing of LT radiators. Except for the controllability occupants have a good appreciation for all LT-systems. In particularly indoor climate is much improved in dwellings with floor and wall heating in relation to previous situations. For LT radiators there is no difference in appreciation of the indoor climate in relation to their previous situation. Heating systems showed many failures during the first years. Remarkable is that the less innovative system, LT-radiators, had the most failures: in 48 of the dwellings one or more failures occurred during the first two years that could not be repaired by the occupants. This score heating is much worse then other household appliances. 18