Monitoring dwelling stock efficiency through energy performance register: Trends in Dutch social housing
Speakers:
Majcen, D.1; Itard, L.C.M. 2; Visscher, H.3
1
OTB Research Institute, Delft University of Technology, Delft, The Netherlands, d.majcen@tudelft.nl
2
OTB Research Institute, Delft University of Technology, Delft, The Netherlands, l.c.m.itard@tudelft.nl
3
OTB Research Institute, Delft University of Technology, Delft, The Netherlands, h.visscher@tudelft.nl
Abstract: In 2002 EU adopted the Energy Performance of Buildings directive which was subsequently adopted by the member states. However, more than a decade later, no national registers of certificates have become available publicly or to research institutions in order to give feedback on the introduced regulation. By exploring the 4 million certificates contained in the Dutch energy performance register we demonstrate the trends in energy efficiency of the dwelling stock in years 2008 – 2012 and discuss the usefulness of the register for energy efficiency monitoring and possible improvements.
Energy label, energy performance register, dwelling stock efficinecy, monitoring Background
Energy Performance of Buildings Directive is, since its first adoption in 2002, the main driver in reducing energy consumption in buildings in Europe. In May 2010, a recast EPBD was drafted as a response to the more ambitious 2020 targets - 20% for energy and 30% for CO2 set by the commission. To ensure that the directive is paving the way towards achievement of the set goals, registers of performance certificates were established nationally in 11 member states [1] with the share of dwellings it contains ranging up to 24% in The Netherlands and UK. However, no in-depth analysis of these data was found during the literature review. The goal of a 110PJ reduction set for the built environment in the Netherlands can be translated into 18% for the horizon 2008 – 2020. To evaluate the progress of the energy saving policies in the Dutch social housing sector, AgenschapNL has in the years 2008 - 2012 commissioned research on the dynamics of uptake of renovation measures. In the mentioned years together it was established that about 950.000 dwellings were made 20 – 30% more energy efficient [2]. This monitoring was indirect and relied on data of questionable quality. However, using the energy performance register as basis, the quality of the monitoring can be significantly improved. This paper investigates overall changes in the stock in 2008 – 2013. A related paper base don similar data by [3], focusses on annunal improvement pace of the dwelling stock.
Dataset properties and methodology Background of the SHAERE database
For the use in this paper, Aedes, a Dutch umbrella organisation of housing associations, has provided us with their register of energy performance certificates (called SHAERE). Since
2010, more than three quarters of all Dutch housing associations report their entire stock to Aedes in the beginning of each year for the previous year (e.g. in January 2014 for 2013). They report the status of their whole dwelling stock which they manage with Vabi Assets software. The software is used for appreciation, rent estimates, plan maintenance and also to order to obtain an energy label certificate according to the Dutch energy label methodology. However, SHAERE is in fact much richer than only official Dutch energy labels, since it consists of all dwellings of participating housing associations at the end of each calendar year, including the most recent interventions and the corresponding energy label (so called pre-label) and energy consumption. Because these annual records of dwelling descriptions have not yet all been registered with the authorities, we will refer to them as pre-labels. Since certificate registration only obligatory at the time of rent or sale, not all dwellings in SHAERE also have a label registered at the RVO (Table 1). In 2013 72% of the pre-labels had a
registered certificate (but this registered certificate may be from before 2011).
Unfortunately, SHAERE only contains the dwelling properties at the end of each calendar year (referred to as the reporting year) and not also the properties at the time of energy label registration (if it did occur). It does, however, contain information of the label category (energy index) and precise date of registration of each registered label certificate. Using the registration year and energy index at registration we can compare the quality of the stock according to their energy certificate with the stock according to the data used in the pre-labels. The description above thus reveals two ways of analysing the SHAERE data – using the information of pre-labels on one hand and the registered label certificates on the other. For more in depth research, pre-labels offer more opportunities due to the fact that all dwelling properties are known for that point in time. Quality of the pre-labels is considered as high as of the registered certificates [3] and when changes have been made in a dwelling, housing associations communicate that quite directly to their consultant, who updates the status in
Year Reg. status Frequency Percent 2010 Not registered 438205 38,68% Registered 694741 61,32% Total 1132946 1 2011 Not registered 246034 20,74% Registered 940033 79,26% Total 1186067 1 2012 Not registered 457542 31,80% Registered 981158 68,20% Total 1438700 1 2013 Not registered 333553 23,03% Registered 1114713 76,97% Total 1448266 1 Total Not registered 1475334 28,34% Registered 3730645 71,66% Total 5205979 1
Table 1: Status of pre-labels in SHAERE
Vabi Assets immediately. Besides more detailed data, another clear advantage of pre-labels is the larger sample. The data was obtained from 243 housing corporations (in 2011 there were in total 289) in The Netherlands and contains 2.083.561 individual dwellings which is 89% of the total Dutch social housing stock. It is important to note, that social housing represents 33% of the Dutch dwelling stock. The dwellings geometry, detailed envelope and installation system characteristics are included, as well as metadata on the inspection and label
registration process. Such rich datasets are pioneering on European level and as such offer good representatively for social housing sector in The Netherlands.
Analysis setup
There are two possible ways to analyse the changes efficiency of the stock, firstly by specifically tracking the dwellings whose energy label have undergone changes during this period (this can also be done by analysing the pre-labels (A) or by analysing only the registered certificates (B). Secondly, we analyse the changes in total pre-label stock (C) between 2010 and 2012 (or in case of limiting the research to registered label certificates 2008 till 2013)
For point A. we first we removed one of the duplicate records, if pre-labels with exactly the same address and the same energy index and reporting year were found. Then we saw that there were a lot of cases with exactly the same address and the same reporting year, but different energy index. In such an instance both of the cases were removed. After this 5.200.505 cases were left. To generate the results, we removed pre-labels that were only calculated once, there were 546.206 of such pre-labels (therefore also 546.206 unique dwellings with a unique pre-label). Out of the remaining records we then obtained first and last record in time, if there was a pre-label reported in each consecutive year from 2010 until 2013, we discarded the 2011 and 2012 records, leaving 1.537.355 dwellings having two different pre-labels.
For B, the analysis is made on the registered label certificates, (n=3.516.467) some of which again had exactly the same address and the same energy index and registration year. We selected a single case from these duplicates and were left with 1.730.367 cases. After this, cases were still found that had exactly the same address and the same registration dates, but different energy index. In this case, we looked at the reporting date to SHAERE and discarded the case with older reporting year, leaving 1.715.669 cases. The final step was the deletion of a handful of cases, which had the same reporting year, and registration date, but different energy indexes, ending in a dataset of 1.714.496 cases, which correspond to individual dwellings. Some of the certificates out of the 1.714.496 were only registered at the RVO once, and are as such not useful to trace changes. We discarded this way 1.230.571
certificates (unique dwellings). Out of the remaining certificates, we retained only the first and last certificate for each dwelling. This sample finally consisted of 233.670 dwellings with two certificates.
Also in C, we looked at both, labels and registered label certificates. Analysis on the pre-labels was simple, since each dwelling is already represented only once in a given year in SHAERE. With the registered label certificates, it was slightly more complicated, since the same certificate could have been reported to Aedes multiple times and the procedure applied in B. was used to isolate 1.714.496 useful records.
Results
Dwellings which have undergone a transformation
1.537.355 out of the total number of dwellings with a pre-label is 2.083.561 have more than two pre-labels. It means that 74% have undergone a change in their pre-label. If we look at the percentages with regard to the total number of dwellings with a pre-label (2.083.561), we can say that 12% had the pre-label improved, 58% had an unchanged label and 4% had a worse pre-label. For the 58% with a constant label it would be interesting to know whether the energy index changes or not (it may be that the label has not changed, but the EI had, indicating a small dwelling improvement). The total number of dwellings with multiple registered certificates in years 2008-2013 is 233.670 which translates into 16 % of the total that has undergone changes. The turnover is much less than in the pre-labelled stock, but of the same magnitude as the improved pre-labels (12%), which tends to show that registration at RVO almost only takes place when the pre-label is improved. 8% of re-registered
certificates had the label improved, 6% had an unchanged label in the first analysis and 1% had a worse label. According to the pre-labels analysis, 12% of the dwellings have undergone a renovation that led to a label improvement in the period 2010-2013, that is on average 4 % per year. According to the analysis of the registered certificates, these figures are 8% in the period 2008-2013, that is on average 1,6 % per year. However, the number of label steps per changed dwelling is significantly higher in the category of registered certificates.
Dwellings with a pre-label (2010-2013)
2083561 100% total stock Average per year
1537355 74% turnover 24,7%
258352 12% improvements 4,0%
1200506 58% stays the same 19,3%
78497 4% worsening 1,3%
284204/336849 0,84 label steps per changed dwelling
Dwellings with registered label certificates (2008-2013)
1754588 100% total stock Average per year
233670 16% turnover 3,2%
116864 8% improvement 1,6%
99721 7% no label category change 1,4%
17058 1% worsening 0,2%
155723/233670 1,16 label steps per changed dwelling
Table 1: Comparison between the three analysis for the dwellings with multiple pre-labels or certificate
Total stock annually
Looking at the distribution of total stock of pre-labels each year (Figure 1), we can observe a positive trend – the percentage of categories A, B and C is steadily growing, whereas the percentage of poor label categories is decreasing. With the current pace, the proportion of B labelled dwellings would reach about 32% by the year 2020, whereas The trend in mean energy index is shown in Figure 4 and would lead to approximately 1,4.
Looking at the annually registered certificates, there are bigger differences between frequencies of each category. It seems that in the recent years, more and more A labelled dwellings get registered (from 2 – 7%) and also dramatic is the rise in registration of B labelled dwellings (8 – 20%). Also the amount of dwellings with a poor label decreased more dramatically than in the analysis of pre-labels. However, given the fact that most certificates were actually issued in the first years (2008 and 2009), no great change can be detected if we observe the label distribution in all certificates available until a given year (green bars in Figure 1). The results are very similar to the distribution of pre-labels.
The comparison with Figures 2 and 3 (for the registered certificates) shows that the trends using registered label are much flatter than using the pre-labels as the basis. If the goals were almost met using the pre-labels as basis, the Dutch dwelling stock has yet a much longer way to go if we look at the registered certificates (the share of B labelled dwellings will be only 22% and not 30% as forecasted by the pre-labels). Similar trends are seen if mean annual energy index is plotted on a graph.
Figure 1: Share of label categories calculated in a given year
0% 5% 10% 15% 20% 25% 30% 35% A B C D E F G A B C D E F G A B C D E F G A B C D E F G A B C D E F G A B C D E F G 2008 2009 2010 2011 2012 2013
% label category in a given year
% certificates registerd in a given year % certificates registerd until a given year % pre-labels each year
Discussion
In the results observed in section 3, there are large differences between results obtained with pre-labels or registered labels when looking at dwelling with multiple records. The turnover is much higher in pre-labels, which is logical, since all dwellings get reported every year and many of them probably had no change occurring. Some possibly had a small improvement, but if the label step does not change, the motivation for reregistration is less strong.
However, the improvement rate seems to be relatively comparable – 12% in the pre-labelled stock and 8% in registered labels. If this is extrapolated to the whole Dutch social housing dwelling stock (2.315.963), each year 92.600 dwellings would be improved using the pre-label data and 61.700 using the re-registered certificates. Both these instances are, however, slightly off from the 135.000 dwelling that were improved in 2011 according to the
monitoring carried out in the past [2]. However, the 12% is close to the goal adopted by Meer met Minder agreement (goal of 300.000 annually improved dwellings), as it can be translated into 280.000 dwelling improved annually, which is good news. Moreover, the 12% rate is also comparable to the results of the previous monitoring (950.000 improved dwellings in 2008 – 2011). Also looking at the energy index, the target of average index 1,25 by 2020 set in seems almost achievable using the pre-labels, but less so using the registered label. The target of 80% of the stock being label C by 2020 might however be overly ambitious.
Overall, the data from the registered certificates are much more conservative than the data from the pre-label, except the average label step improvement. However, the fact that the
Figure 2 and 3: Trends in proportion of label categories (all re-registered label certificates) 0% 5% 10% 15% 20% 25% 30% 35% 2008200920102011201220132014201520162017201820192020
Shaere of certificates along with the 2020 forecast - registered labels C label D label E label F label G label A label B label -5% 0% 5% 10% 15% 20% 25% 30% 35% 40% 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
Share of certificates along with the 2020 forecast - pre-labels C label D label E label F label G label A label B label
Figure 4: Decreasing trend in energy index (dashed line – registered labels, full line - prelabels) 1,2 1,3 1,4 1,5 1,6 1,7 1,8 1,9 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
Energy index trend and the 2020 forecast
frequencies of label categories in registered labels are coming closer to the frequencies of labels as time passes (Figure 2), speaks towards the future focus being on investigation of pre-labels, also because as stated in the 2.1, this data is much richer.
Conclusions and future research
The results show that the Dutch social housing stock is on a good way to improve its energy performance, however, the measures taken should probably be strengthened if the goals are to be achieved. The biggest problem of this study are the uncertainties regarding data quality. From the interviews with Vabi and Aedes, we tend to conclude that the pre-labels are more accurate because they represent the actual state of the dwelling stock at the end of each year. The registered certificates are supposed to be less accurate because the certificate is valid for 10 years and housing associations do not always want to re-register a dwelling, also when they could ask for more rent with a higher label. Further study should show if this hypothesis is right. As described in chapter 2, the composition of the database was complex, which significantly impacted the usability of the data. In the future better documentation of the data is necessary if the database is to be used further for research purposes. Further study is planned into the effectiveness of the measures implemented in the SHAERE, however, the fact that for registered labels, the only information available is the energy index and label category without any dwelling characteristics, limits the analysis to investigation of the pre-labels for which the dwelling properties are available, but the date of the last change is not very accurate. This relates to another goal of the study we plan, which is the coupling of the dwellings with their annual actual gas consumption. Since large discrepancies were found between actual and theoretical energy consumption in the past [4], insight into actual effectiveness of renovation measure implemented should be more than valuable. However, the fact that a precise date of last dwelling transformation is not known hinders the coupling greatly. As was mentioned before, this dataset is the first of its kind on European scale and although it offers great opportunities, it still has many weaknesses which should be upgraded in the future.
References
[1] Europe’s buildings under the microscope, Country-by-country Review of the Energy Performance of Europe’s Buildings, BPIE, 2011.
[2] Hezemans A., Marquart E., Monné T., Monitor Energiebsparing Gebouwde Omgeving 2012, Agentschap NL, Juni 2012.
[3] Fillipidou F., Niebor N., Visscher H., The pace of energy improvement in the Dutch non-profit housing sector, Submitted on 26 May for WSB14 conference in Barcelona
[4] Majcen D., Itard L., Visscher H., Theoretical vs. actual energy consumption of labelled dwellings in the Netherlands: Discrepancies and policy implications, Energy Policy 54 (2013), pp. 125–136.
