Technologies

Interactive Case Study Technology Dashboard

Interactive Case Study Dashboard

nZEB Technologies

For realising nearly zero-energy buildings (nZEBs), which are cost-efficient for all stakeholders throughout the lifecycle, the knowledge about the most important technologies and solution sets as well as possible cost developments of these technologies is essential.

The focus should always be on the minimization of energy demands (heating, cooling,ventilation, lighting) by passive approaches. The remaining energy demands must be supplied by a large extent from renewable energies onsite and as efficient as possible.

Passive approaches and active technologies to supply heat, cold, fresh air and generate energy on-site from renewable sources are the heart of each building and nZEB. An optimal combination of the available approaches and technologies can lead to high cost savings today and in the whole life cycle of a building by (i) minimize initial and replacement investment costs and (ii) minimize operation and maintenance costs. Optimal building design and the application of passive approaches play a key role here as they not only reduce the energy demand and cost during operation, they also reduce the needed installed power and thereby investment costs for active technologies.

Besides the considerations and assessments from a building
owner/ operator perspective, additional considerations and factors gain importance as buildings more and more become an active and interactive part of the overall energy system. How buildings can support the integration of fluctuating renewable energies also on a broader scale is therefore also assessed and described in the following.

Many nZEB technologies do already exist today. However, their current market share is comparably low. With an increasing market share and technological developments, cost reductions are expected for most relevant technologies. The following technologies were identified as most important for nZEBs based on the various case study buildings of the CRAVEzero project and further literature review:

  • Renewables: PV and solar thermal systems
  • Heating: heat pumps
  • Air conditioning
  • Central and decentralized ventilation with heat recovery
  • Thermal and electrical storage
  • Insulation and other passive strategies

A highly insulated building envelope forms the basis for nZEBs.
For the calculation of possible future cost reductions, a suitable methodology based on past market developments and the current status of a specific technology (efficiency, costs) was identified and applied. With the top-down experience curve method based on learning rates for each technology and a bottom-up method to identify specific cost drivers and their respective cost reduction potentials, the cost reduction potentials of the mentioned technologies and approaches were calculated.
The central assumption of the top-down approach is that costs decrease concerning the increased cumulative production due to learning effects. More experience through the market development leads to cost reductions through technological improvements and economies of scale.
For the bottom-up method, more detailed information is needed, which is not available for all assessed technologies. Therefore, the method was only applied for PV systems, solar thermal systems and stationary lithium batteries as they are seen as technologies of major importance for nZEBs and the energy system as a whole.
For the top-down approach and to develop experience curves for the assessed technologies, current cost and cumulative volume levels, possible market development as well as learning rates based on past developments were determined. Therefore, a cost database with all data was developed, which can be accessed in the CRAVEzero-pinboard. The focus of the analyses was the EU. However, for several technologies, the availability of data was limited, and the analysis was therefore limited to Germany.
This calculated cost reduction potentials until 2050 vary from approx. 1% to 65%. Stationary batteries have the highest potential with 65%, oil and gas boilers have the lowest potential of less than 10%.

Most cost reductions due to optimizations are expected to be achieved in storage systems and renewable and energy-saving technologies such as PV and ventilation with heat recovery.
The generation and storage of electricity and heat from renewable energies provide technological combinations in buildings with considerable cost reduction potential. They can increase the self-sufficiency of buildings and reduce their carbon footprint.

Table: Ranges of cost reduction potential in 2030 and 2050

Technology

Potential range until
2030

Potential range until
2050

PV                              

20.0% – 29.0%

41.0% – 55.5%

Solar thermal

9.1% – 23.9%

22.0% – 50.8%

Gas boiler:

4.1% – 9.2%

4.9% – 11.1%

Oil boiler

0.3% – 0.7%

0.8% – 1.9%

Biomass boiler

7.2% – 13.4%

9.6% – 17.8%

Aerothermal HP         

4.8% – 21.6%

11.0% – 43.9%

Ground source HP     

5.9% – 25.8%

7.9% – 33.4%

Thermal storage

9.5% – 26.9%

15.7% – 41.4%

Electrical storage

34.9% – 62.7%

47.9% – 77.7%

Air conditioner

9.3% – 25.2%

17.8% – 44.3%

Decentralised ventilation

30.3% – 49.3%

40.4% – 62.2%

Centralised Ventilation

24.4% – 41.0%

34.6% – 55.1%

Figure: Cost reduction potentials of major nZEB technologies calculated with the top-down learning curve approach.

Figure: Cost reduction potentials of major nZEB technologies calculated with the top-down learning curve approach.

The derived cost reduction potentials comprise several uncertainties and many unexpected changes in policy and the economy (like e.g. the current Corona pandemic) may occur until 2050. These changes can influence specific technologies and the building sector as a whole by changing targets or promoting and subsidizing specific technologies etc.
With the bottom-up analysis several specific potential cost reduction drivers for PV, solar thermal and electrical storages were identified. For PV, the most important factors are efficiency optimizations and lower material input for the modules. For solar thermal systems, the major factors are using less material and switching to cheaper materials. Furthermore, simplification of or changes in production methods and faster assembly could lead to cost savings in the future. The latter is also highly dependent on processes in planning and construction. For electrical storages, cost reductions can be achieved through economies of scale and technological improvements like an increased energy density and the reduced and more cost-effective use of materials.
Besides the described mainly active technologies, a central part of the solution sets/ low LCC nZEBs are low-tech, passive strategies.

Optimal technology sets

CRAVEzero Case Study – Alizari (Bouygues)

The project CRAVEzero mainly builds on twelve case studies provided by the project partners. The case studies are located in Austria, Italy, France, Germany and Sweden. For several case studies, parametric simulations have been conducted. From the results, the variants with the highest and lowest net present value (NPV) as well as the highest and lowest CO2 emissions were identified. For these variants, similarities and main differences were assessed to identify drivers for realizing cost optimal nZEBs.
The analysis of the variants with the highest and lowest NPV as well as the ones with the highest and lowest CO2 emissions based on the parametric analysis conducted in WP06 shows that non-technical factors have a strong influence on the energy demand, emissions and NPV of a building. These are (amongst others) the user behaviour and climate conditions. Furthermore, a building envelope at least having a nZEB standard – in many cases even a higher standard – is an important component of low emission and low-cost buildings. In these buildings, DHW is in most cases dominating the final energy demand. An interesting finding of analyzing the variants with the lowest NPV and lowest emissions is that in most cases these variants have less technical installations than the base cases and can be considered as low tech buildings. Minimizing the technical installations is, on the one hand, reducing the investment as well as operation and maintenance cost and on the other hand minimizes the auxiliary energy demand. Furthermore, the active use of solar energy (mainly PV, in several cases, also solar thermal) is essential for achieving minimal CO2 emissions. Solar technologies are often competitive with other technologies and especially in the case of PV, which has positive effects on the costs/ NPV. From the analysis, possible best solutions achieving low emissions with comparably low costs were identified. As an example, possible best variants of the case study Résidence Alizari are shown in the Table below.
The analyses of the passive approaches and also of the results of the parametric analysis show that there is no one optimal solution for every setting and side conditions. Furthermore, the goal (minimal costs, minimal emissions) of a design team/ building owner is strongly influencing the technology set and building concept.

Table : Variants with low CO2 emissions and comparably low costs of the case study Résidence Alizari based on parametric simulations. The shown variable number is based on the results matrix of the parametric analysis and is equivalent to the number of the variant in the interactive case study dashboard in the CRAVEzero-pinboard.

Variant Number

12098

12099

11907

12162

12163

Envelope insulation

External wall
250 mm

External wall
250 mm

External wall
250 mm

External wall
300 mm

External wall
300 mm

PV

30 kWp;
efficiency 15 %

34 kWp;
efficiency 17 %

34 kWp;
efficiency 17 %

30 kWp;
efficiency 15 %

34 kWp;
efficiency 17 %

NPV [€/m²]

1,512

1,516

1,517

1,518

1,521

CO2 emissions [kgCO2/(m²a)]

23.31

23.14

23.61

23.22

23.05

Exemplary technical solution sets of case study Alizari

CRAVEzero – The Role of life-cycle costs in NZEB projects

Role of life-cycle costs in NZEB projects

Submitted by Baerbel Epp on February 4, 2020 on solarthermalword.org

How much does it cost to construct, run and maintain a Nearly Zero Energy Building? What energy efficiency and renewable options could work best for a given project? Answering these and other questions is the aim of CRAVEzero.eu, a new, interactive online platform. It supports architects and planners during the design and construction process by offering a set of software tools to estimate how much money will be needed for a Nearly Zero Energy Building (NZEB) over its lifetime. One of the properties that have been analysed as part of CRAVEzero is Isola nel Verde, a block of flats in Milan, Italy (see image). Image: Isola nel Verde   “We carefully examined the cost structure and planning processes of 12 NZEB demonstration projects in Austria, France, Italy and Sweden to identify a cost base for the purchase, maintenance and operation of different components, including heat recovery systems, solar thermal installations and building envelopes,“ said Tobias Weiss, who works as the project manager of CRAVEzero at AEE INTEC based in Austria. The lessons learned from implementing these showcase projects, which focus on multi-storey residential and office construction in Europe, have since been shared with the entire sector.   “Using real-world data from these demonstration projects, we carried out calculations for half a million variants, which you can search for online by going to the Interactive Case Study Dashboard,“ explained Weiss. The dashboard can be found on the CRAVEzero Pinboard, a web page that is currently being beta-tested and includes a number of tools offering support for planners of NZEB projects.  

This chart shows the life-cycle costs of different variants for Isola nel Verde in Milan, Italy, in relation to their specific primary energy demand. Combinations which are subject to the same efficiency standards for building envelopes, heating and ventilation, and solar energy systems are highlighted in the same colour. For calculation purposes, it was assumed that loans would run for 25 years and carry 3 % interest at 2 % inflation and a nominal discount rate of 3 %. Source: CRAVEzero   The chart above shows the life-cycle costs (LCC) of hundreds of variants for Isola nel Verde in Italy. Specific costs range from 2,800 to 3,600 EUR/m2 (factor: 1.3). The cost estimate for the actual building was 3,615 EUR/m2, split between 1,899 EUR/m2 (53 %) for the building itself and 1,716 EUR/m2 for its operation (energy, maintenance and similar).    Regarding primary energy demand, some variants even differ by a factor of 2. If Isola nel Verde had been constructed in line with common building regulations, which require the addition of an air source heat pump (green dots) but no ventilation system, primary energy demand would have been somewhere between 140 kWh/m2 and 210 kWh/m2 a year. The most environmentally friendly variants include 72 m2 of solar collector area and a 14 kWp PV generator (purple dots) and reduces yearly primary energy demand over the entire lifetime of the building to about 100 kWh/m2.   Dashboard for benchmarking project LCCs “Calculating LCC variants is therefore a vital step in the integrated planning process of zero-energy buildings. Else, you run the risk that architects and engineers optimise components with only their specific area in mind and lose sight of shared goals,” said Weiss.   Variants including solar thermal systems (see the purple dots in the chart above) have the lowest life-cycle costs of all Isola nel Verde options. These systems may lead to a slight increase in the initial investment amount but will save annually increasing amounts of money because of rising energy costs over the 20-year lifetime of a collector. For example, in Europe, up to 50 % of the copper that is used as a key material to make solar thermal circuits can later be recycled. According to the European Copper Institute, recycling reduces energy consumption by up to 85 % compared to primary production.    Dashboard users can filter by building envelope, efficiency standard and heating or air conditioning system to find variants. “A great plus of the dashboard is that it lets you compare your building project with the variants available online, so you can see where you stand regarding life-cycle costs, as well as heat and primary energy demand,” explained Weiss.    Integrated design The Case Study Dashboard is one of several functions provided by the CRAVEzero Pinboard. Another website feature is the Interactive Process Map, which shows the design process of NZEBs. Integrated design is essential to their construction; in this context, integrated means engineers and architects work together closely to develop the most innovative and effective solution for a given project and monitor compliance with standards and practices during its implementation. Process diagrams are then used to help planners set out the responsibilities of each partner in the project, plus point out possible bottlenecks or weaknesses which have hampered previous endeavours.  

Further information:

CRAVEzero project website: http://www.cravezero.eu

CRAVEzero Dashboard: https://www.cravezero.eu/pboard/Dashboard/DBInfo.htm

Interactive Process Map: https://www.cravezero.eu/pboard/PMap/ProcessMap.htm

Life Cycle Cost calculation

Figure: LCC calculation in CRAVEzero

The ISO 15686-5:2008 provides the main principles and features of a
LCC calculation, while the European Code of Measurement describes an
EU-harmonised structure for the breakdown of the building elements, services,
and processes, in order to enable a comprehensive evaluation of the building
life costs in this study.

According to the above-mentioned ISO standard, the LCC of a building is the Net Present Value (NPV), that is the sum of the discounted costs, revenue streams, and value during the phases of the selected period of the life cycle.

The NPV is calculated as
follows:

Construction, operation and maintenance phases have been considered, whereas end-of-life stage was discarded as the analyzed period is 40 years, less than an average building lifespan.

LCC calculation was implemented in two steps along CRAVEzero
project. First, for the analysis of the 12 case studies coming from project
partners. Second, for the parametric analysis.

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Results of optimised nZEB parametric models

Cost performance (EUR/m²) of the case study Aspern IQ over the whole life cycle of the building; comparison of nZEB variant with a building accord-ing to the CRAVEzero approach and the average value

Already
today buildings can be realised in the nearly zero and plus energy standard.
These buildings achieve extremely low energy demands and low CO2
emissions and can be operated economically. For this reason, the motivation in
the CRAVEzero project is not only based on the energy characteristics of
buildings, but also on their life cycle costs. However, the broad market
deployment of these buildings is progressing very slowly so far, as methods and
processes for the cost-optimal integration of efficiency measures and renewable
energies are not yet sufficiently described and therefore not yet familiar. As
a consequence – many poorly planned buildings are criticised for the fact that
the actual energy consumption of highly efficient buildings is higher than the
predicted demand and that high-efficiency standards are expensive and
uneconomical. The influence of the user behaviour of such energy-efficient
buildings is another aspect, which has to be considered to evaluate the impact
on the energy consumption of the building.

“bubble chart” of the case study Aspern IQ; bubble size indicates the average CO2 emissions; bubble position is determined by average investment costs and average life cycle costs
“bubble chart” of the case study Aspern IQ; bubble size indicates the average CO2 emissions; bubble position is determined by average investment costs and average life cycle costs

The
identification of suitable methods for the energetic-economic optimization of
highly efficient buildings in all life cycle phases is a prerequisite for the
broad market implementation.

This
method was developed earlier in the CRAVEzero project and documented in
Deliverable D6.1 “Parametric models for buildings and building clusters:
Building features and boundaries”.

In this
Deliverable D6.2, the method was applied to the five CRAVEzero case studies Aspern
IQ, Alizari, Isola Nel Verde, Les Heliades and MORE to perform parametric
calculations and to perform multi-objective energy and cost analysis over the
life cycle of the buildings.

Specific costs (EUR/m²) in the different phases of the case study Aspern IQ over the whole life cycle of the building; range between the different parameters indicated as minimum (min), average and maximum (max) values; per-centages represent the deviation from the average value

In total, more than 230,000 variants were calculated and analysed, with the key performance indicators: financing costs, net present value, balanced primary energy demand and balanced CO2 emission. The calculation results can be found in this report as well as on the CRAVEzero pinboard: http://www.cravezero.eu/pinboard/Dashboard/DBInfo.htm

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Energy flexible building managing models

Already
today buildings can be realised in the nearly-zero and plus energy standard.
These buildings achieve extremely low energy demands and low CO2
emissions and can be operated economically. For this reason, the motivation in
the CRAVEzero project is not only based on the energy characteristics of
buildings, but also on their life-cycle costs and building operation, which is
supporting the large-scale integration of fluctuating renewable energies in the
building itself, but also in higher-level electricity grids. For the
integration of fluctuating renewable energies (i) the integration and
intelligent operation of storages (electric and thermal) as well as smart
operation and management strategies are needed.

CRAVEzero_D43_Energy_flexible_building_managing_models

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Parametric models for buildings

Download the full report here:

Figure1: Analysis of the balanced primary energy demand related to the net present value for the different technology combinations for case study Solallen.

Already today buildings can be realised in the nearly zero and plus energy standard. These buildings achieve extremely low energy demands and low CO2 emissions and can be operated economically. For this reason, the motivation in the CRAVEzero project is not only based on the energy characteristics of buildings, but also on their life-cycle costs. However, the broad market deployment of these buildings is progressing very slowly so far, as methods and processes for the cost-optimal integration of efficiency measures and renewable energies are not yet sufficiently described and therefore not yet common. As a consequence – many poorly planned buildings are criticised for the fact that the actual energy consumption of highly efficient buildings is higher than the predicted demand and that high-efficiency standards are expensive and uneconomical. The influence of the user behaviour of such energy efficient buildings is another aspect, which has to be considered to evaluate the impact on the energy consumption of the building.

The identification of suitable methods for the energetic-economic optimisation of highly efficient buildings in all life-cycle phases is a prerequisite for the broad market implementation.

On the basis of the results, the statement is confirmed: nZEBs are economical. It can now be shown that the additional costs of efficiency measures are so low that highly efficient buildings have the lowest life-cycle costs. nZEB measures only have a small percentage influence on construction costs, but can reduce CO2 emissions many times over. When considered over the service life, these measures are usually cost-neutral or even economical as can be seen in Figure 2.

Figure2: net present value (€/m²) relation to the balanced CO2 emissions (kgCO2/(m²a)) of all variants of the case study Solallén

Figure3: Cost performance (€/m²))of the case study Solallén over the whole life-cycle of the building; comparison of nZEB variant with a building according to the CRAVEzero approach

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Energy-Flexible nZEBs

The increasing share of fluctuating renewable energy generation in the electricity grids requires technical measures, new market designs and models to balance generation and demand for electricity on the demand and supply side. As buildings are major energy consumers in the energy system and electricity for heating, domestic hot water and cooling, as well as on-site electricity generation from renewables are increasing, the integration of building energy systems/ buildings in the energy system is gaining importance. Renewable electricity is generated on-site, stored in batteries, which could also be used for balancing the local distribution networks, heat-pumps and electrical vehicles are new electrical consumers in buildings with relatively high connected power,…there are many new and already established technologies, which have to be integrated into the system and be operated in a way stabilizing the electricity grids.
There are several different options, flexibility goals and KPIs discussed in the field of energy efficiency and flexibility. Furthermore, there are different options and needed technologies to provide flexibility. In the CRAVEzero report ‘Energy flexible building managing models’, these are described in detail. Furthermore, technologies and different methods were applied in some of the CRAVEzero case study buildings. The options are compared using three different approaches/ KPIs, namely:

  • Self-sufficiency/ autarky rate based on Results of the tool PVopti
  • Analysis of the Grid Support Coefficient GSC developed at Fraunhofer ISE
  • Analysis of the Smart Readiness of the buildings based on the current status of the definition of the Smart Readiness Indicator, which might be introduced on the European level in the future.
    Similarities, as well as contradictions of the approaches, are highlighted. The aim of the work is the development and description of models and methodologies for (i) continuous commission of buildings and (ii) building-grid interaction with a focus on the on-site use of renewable energies. Thereby, two major challenges of the future are addressed, which are (i) the reduction of the energy use in buildings and avoidance of malfunctions in the building energy system and (ii) the integration of fluctuating renewable energies in the electricity grid by adjustments in the building operation.
    The process of continuous commissioning is described based on a detailed literature review as well as on results from projects focusing on fault detection in large and complex building energy systems.
    For the integration of renewable energies in the electricity grid by an adjusted building operation, the definitions and findings from the IEA EBC Annex 67 “Energy Flexible Buildings” are the basis. Possibilities for an improved building-grid interaction are described qualitatively and assessed quantitatively using different approaches/ tools and a comparison of the respective results. The quantitative analysis uses the PHPP-models of case studies as a starting point. With the tool PVopti , the self-consumption and autarky level of the base case and several other technology sets are assessed, and for each case hourly electricity profiles are generated. The hourly profiles are used in a second step to analyze the grid supportiveness of the building/ technology set using a methodology and indicator (Grid Support Coefficient GSC) developed at Fraunhofer ISE. Also, the case study buildings assessed in detail are rated using a simplified method for rating the Smart Readiness of Building (Smart Readiness Indicator SRI) based on the proposed Simplified online quick–scan described in (Reynders, 2019).
    The differences between the approaches and the respective results are compared, analyzed and critically discussed. The aim is to identify different implications for the building technology sets from the different approaches resulting from the different focuses (self-consumption, grid-supportiveness,…).
    Buildings interact with surrounding energy systems by importing and exporting energy (Salom et al., 2014). Usually, the focus is the interaction with the electricity grid. With the increasing usage and integration of fluctuating renewable energy technologies like wind and photovoltaic in buildings and electricity grids, the interaction between all participants (energy consumers and producers, as well as prosumers, is gaining importance. In order to support the integration of fluctuating renewables the import and export of buildings should be oriented on the current state of the superordinate power grid by increasing the flexibility of the energy supply and demand of the buildings. In (Weiß et al., 2019a) flexibility is described as the maximum time a power draw can be postponed or additionally consumed at a specific moment during the day.
    In (Voss et al., 2010), the importance of building-grid interaction to realize net-zero-energy buildings (NZEBs) is emphasized. The interaction/ energy exchange with a grid infrastructure helps to overcome limitations of on-site seasonal energy storage. Grid interaction is defined in (Voss et al., 2010, p. 2) as “the temporal match of the energy transferred to a grid with the needs of a grid”. In the following important terms and approaches to manage and optimize the interaction between energy grids and buildings as well as strategies to increase the intelligence of energy systems and buildings are described. Furthermore, approaches to quantify the ability and level to operate buildings in a way, which is helping to stabilize and manage the grids and thereby integrate an increasing share of fluctuating renewables are introduced.
    Demand Side Management (DSM) can be used to manage the load curve of buildings, such as shift demand in time (load-shifting), reduce the peak in the energy demand (peak-clipping/load shaving) or temporally increase the load when the incentives are high, or the electricity prices are low (valley-filling) – see Figure 43. The relevance and possibilities for the different DSM approaches in several European countries.

DSM is defined from a utility perspective as “the planning and implementation of those electric utility activities designed to influence customer uses of electricity in ways that will produce desired changes in the utility’s load shape” (Gellings, 1985), and can be divided into two categories like energy efficiency (EE) and demand response (DR) (Palensky and Dietrich, 2011). The benefit of DR strongly depends on the available energy flexibility and successful implementation of DR programs. Hence, most state-of-the-art literature is focusing on demonstrating to what extent this can reduce energy cost, shift peak power, increase the use of local renewable electricity production, or achieve stability in the power grids by utilizing the flexibility of buildings.
In this context, the term “grid-supportive” operation of buildings is introduced and discussed in science, e.g. in (Klein, 2017). The goal of analyzing and quantifying the grid supportiveness is to understand how and to what extent buildings can contribute to “efficient integration of a high share of intermittent renewable energy into the energy system” (Klein, 2017, p. 17). The focus is on the support of the overall upstream energy system, not only local/ regional grids. “Grid-supportiveness” is defined by (Klein, 2017) as an operation of variable electrical loads in a way that they consume power predominantly in periods with low relative electricity demand in the system. Thereby, not only power load needs are considered, but also the availability of fluctuating renewable energies. On the other hand, a grid-supportive generator produces mainly when the relative electricity demand in the whole energy system is high (Klein, 2017). The contrary behaviour is termed grid-adverse. For measuring/ quantifying the grid-supportiveness, (Klein, 2017) developed the absolute Grid Support Coefficient GSCabs and the relative GSCrel.
One of the key barriers jeopardizing the market uptake of smart technologies is the lack of clarity about the energy benefits. There are few studies about the impacts of implementing smart home devices in buildings, and there is a lack of independently verified empirical data on savings impacts (Urban et al., 2016), evaluated with a shared approach. The EPDB Recast 844/2018 (The European Parliament and the Council of the European Union, 2018) introduced the Smart Readiness Indicator (SRI), in order to raise the awareness amongst building owners and occupants of the value behind smart devices and services, giving confidence to the occupants about the actual savings of those new enhanced-functionalities. It, therefore, measures the readiness of the building “to adapt the operation of buildings to the needs of the occupants and the grid and to improve the energy efficiency and overall performance of buildings“ (The European Parliament and the Council of the European Union, 2018).
From the view of a building, the logic behind this EPBD amendment is: It is intelligent only with minimum equipment of smart technologies and services. What might be missing, displaced or even able to generate resistance:

  • These technologies and services do not guarantee that the building is intelligent in the context of the surrounding energy networks (electricity, heat and gas) or that it helps to lower the CO2 emissions of the overall energy system. In the context of a neighborhood or the surrounding network, however, the energy flexibility and “smartness” of buildings are essential resources for reducing CO2 emissions at this level, in line with the IEA EBC Annex 67.
  • Measured or achieved “smartness” could cause additional costs, which preclude the required affordability of housing. And there are fears that “grid-supportiveness” – if it is applied – would by no means be adequately remunerated by the utilities.
    A consortium led by the Flemish Institute for Technological Research NV (“VITO”) has been awarded the contract for the implementation respectively the concept of the SRI. If their proposal is accepted by the European Commission through parliament and council, the implementation respectively the ascertainment will be up to the individual states. The preparation of a possible national specification of the SRI as well as the possible integration in the process of energy performance calculation can still be influenced since the preparation process is on-going.
    AEE INTEC is involved in the development of the calculation methodology, which is based on a technology and services rating system, weighting different services by their functionality level affecting predefined impact criteria (Reynders, 2019; Verbeke et al., 2018). Such effects are pre-calculated for the smart devices and services available on the market, but they are not associated either to physical nor to performance quantities. This should be noted and kept in background knowledge when new SRI developments are integrated into the work in CRAVEzero to assess the technologies’ and building services’ smartness found within CRAVEzero demonstration projects to learn from.

The case studies “Brussels” and “Moretti More” were analyzed concerning different KPIs, namely self-consumption, autarky GSC with respect to EEX prices, GSC for residual load and the smart readiness of the buildings. For all KPIs except the smart readiness several variants were assessed to identify the driving (technical) factors. However, a positive factor for increasing e.g. the self-consumption is not necessarily positive for the GSC and vice versa. The main positive and negative factors identified for the case study “Parkcarré” are summarised in Table 10 and for “Moretti More” in Table 11.
The main drivers for a high self-consumption are the installation of electricity storage and the size of the PV-system in relation to electricity consumers. Thereby, the presence of large electricity consumers especially in summer (cooling units, heat pump) is a crucial factor as well. Generally one can say the smaller the PV-system compared to the electricity demand, the higher the self-consumption as (almost) all electricity is used on-site throughout the year. The challenge in buildings without high electrical demands in summer (high PV generation) is the usage of the generated electricity in the summer months. For a high autarky rate as well as good GSC values however large PV systems are positive.
For good GSC values, the installation of battery storages, as well as the use of electricity using heating systems, is positive, especially when a PV system installed. In climate regions with mainly heating demands a large PV system in combination with heat-pumps is increasing the GSC concerning EEX prices.
The absence of large electricity consumers, especially the absence of heat pumps with thermal storages, is a crucial part for the self-consumption and GSC as this is (i) affecting the possibility to use PV electricity generated on-site and (ii) affecting the load-shifting possibilities, which are necessary to operate a building grid-supportive. Bivalent heat-pumps thereby even offer higher shifting/ switching potentials and are also positive for the autarky rate.
Especially concerning the self-consumption and autarky, the followed strategy strongly affects the technical installation needed; to increase the self-consumption by trend small PV systems are positive, for a high autarky large systems are necessary. Furthermore, it is crucial that the PV system is sized accurately to the demands of a respective building and sufficient storage possibilities are available.
As the analysis of the smart readiness is based on a more qualitative approach positive and negative factors for the SRI are not included in the summarising tables below. The dimensioning of renewable energy technologies on-site is not influencing the SRI result, but the presence of these technologies. However, what is more important is the availability of storages and the controllability / usability of these storages based on external (grid) demands. Thereby, the installation of batteries, which is positively influencing all other KPIs, has also a positive effect on smart readiness. For a high SRI-score the controllability and control strategies supporting the stability and management of higher level grids are positive. Implementing these strategies in buildings is also supporting the increase of the self-consumption, autarky as well as the GSC. The quantitative effects were not assessed in this study as detailed building models and optimizations would be needed for the analysis, which was not part of the project. It can be concluded however that considering the high level services described in the SRI services catalog is positively affecting all other quantitative KPIs assessed in the frame of this study.

Table: Comparison of factors positively and negatively affecting the assessed KPIs in the case study “Parkcarré”

 

Self-consumption

Autarky

GSC_EEX

GSC_Residual

Positive

Battery storageAccurate dimensioning of PV
in relation to el. demand (by trend smaller PV)Installation of heat-pump

Large PV-systemLarge battery storageNo big el. consumer like
heat-pump during winter (bivalent heat pumps achieve better results)

Medium – large PV system in combination with heat pump and battery
storage

Heat pump + Large PV systemIf no heat pump and Battery installed, smaller PV-system positive

Negative

No big el. consumers in summerNo battery storageToo large PV system

No Battery storageSmall PV systemHeating system only using
electricity à bivalent heat-pumps better

Non-electric heat generation / district heat à only low shifting potentialNo Battery storage

Non-electric heat generation / district heat à only low shifting potential No Battery storage

Table: Comparison of factors positively and negatively affecting the assessed KPIs in the case study “Moretti More”

 

Self-consumption

Autarky

GSC_EEX

GSC_Residual

Positive

Battery storageAccurate
dimensioning of PV in relation to el. demand especially in summer

Bivalent heat pumpLarge PV systemBattery storage

Installation of
battery + large PV

BatteryOptimisation of
operation

Negative

Large PV-systemNo battery storage

No battery storageSmall PV system

Large PV without
battery

Installation of PV

The chapter aimed to develop and description models and methodologies for a continuous commission of buildings and building-grid interaction with a focus on the on-site use of renewable energies. The chapter thereby addresses two major challenges of the future:
• Reduction of energy use in buildings and avoidance of mal-functions in building energy systems
• Integration of fluctuating renewable energies in electricity grids by adjustments in the building operation
The process of continuous commission is described based on a detailed literature review as well as on results from projects focusing on fault detection in large and complex building energy systems. The importance for a reliable and robust operation of a building is highlighted and suggestions for the integration of continuous commission in the building life cycle are provided.
For the integration of renewable energies in the electricity grid by an adjusted building operation, definitions and findings from the IEA EBC Annex 67 “Energy Flexible Buildings” are the basis. Possibilities for an improved building-grid interaction are described qualitatively and assessed quantitatively. Therefore, PHPP-models of case studies and the tool PVopti are used to assess the self-consumption and autarky level of several technology sets are assessed. The results show that an adequate sizing of on-site renewable energy technologies in combination with electrical and thermal storage is essential. A difference between the goal of increasing the self-consumption and increasing the autarky is the size of the on-site renewable generation. While for a high autarky rate a high generation capacity is needed to provide the needed electricity also in times with low specific on-site generation this approach reduces the self-consumption in times with high specific on-site generation. In the case study “Parkcarré” self-consumption rates between 19 % and 100 % and autarky rates of 14 % to 77 % are achieved. The variants with a high autarky always have a relatively low self-consumption compared with similar technology sets and vice versa. Variants with a large PV system and battery but no heat pump have a high autarky rate (a large part of the electricity demand during winter can be provided by on-site PV generation). On the other hand variants with a small PV system and a heat pump have high self-consumption but a very low autarky. Similar results are obtained in the case study “Moretti More”. However, due to a more constant electricity demand throughout the year due to the electrical cooling units installed, the importance of a battery for both, the self-consumption and autarky, is lower than for the case study “Parkcarré”, in which the electricity demand fluctuates more throughout the year. The right dimensioning of the PV system is of major importance in this case.
With the tool PVopti, also hourly profiles for the electricity purchase from the grid were generated, which are used to analyze the grid-supportiveness concerning two external grid signals:
• EEX-prices
• Residual load
Almost all analyzed technology sets are grid-adverse and no set is really grid-supportive. However, the technologies installed and combined offer the possibility to operate the buildings grid-supportive. In order to increase the grid-supportiveness (GSC) the control strategies of single technologies as well as the whole building energy system have to be adjusted. Especially the use of storages and the operational times of large electricity consumers like heat pumps and cooling units are crucial. To quantify the effects of different control strategies, detailed simulations and optimisations are required, which were not part of this study.
In addition to the quantitative assessment, the smart readiness of two case study buildings is rated using a simplified method based on the proposed simplified online quick–scan for the SRI. Here, only the base case (as built / as planned) is rated. Both buildings achieve an SRI below 50 %. Especially concerning on-site energy savings and comfort, both buildings show a good performance, which can be explained with the focus on energy demand reductions and high comfort in buildings in the past years. The flexibility and smartness of building operation is just starting to gain importance and the current energy markets are still not offering promising business cases for a smart and flexible operation. However, the topic will gain importance in the future and many technologies currently installed in buildings already offer an increased flexibility with some adjustments in control strategies (thermal storages, heat pumps).
Besides the technical implementation, the market design including sufficient incentives to provide flexibility in / of the building for the operation and management of higher-level electricity grids has to be adjusted. Currently, only large switchable and shiftable loads can participate in the electricity market. However, the required power for participation is much higher than the power most buildings can provide. Different approaches to close the gap are currently assessed in different projects. Possibilities are e.g. pooling of many small loads to reach the required load size, lowering the required size or new ways of trading amongst participants in the energy markets.
Summing up, the addressed KPI strongly influences the technologies needed. Especially the autarky rate has very different needs compared to the other KPIs. Furthermore, most technologies needed for a flexible building operation are already available. However, some are still comparably expensive and therefore not widespread. The main challenge is the operation and management of buildings in a way that renewable energy can be integrated into the energy system on different levels (on-site, regional, national, European). Therefore, on the one hand control strategies in buildings have to be adjusted and optimized, on the other hand adequate grid signals have to be available for building management and control systems.

nZEB technology guideline is online

Download the full report here:

Different technologies are necessary to achieve the energy standard of nZEBs.​​ They can be summarised in three​​ main categories​​ (i)​​ Passive Energy Efficiency solutions, (ii)​​ Active Energy Efficiency solutions​​ and (iii)​​ Renewable​​ Energies. All approaches/ technologies are needed in order to realise nZEBs. And all of them play a major role in the CRAVEzero frontrunner buildings!

An excellent thermal insulation​​ and air-tightness of the building are of major importance, which can be seen in the rather low U-values of the building envelope elements in the case study buildings (opaque elements​​ between​​ 0.07 and 0.25​​ W/(m²K), windows mainly between 0.7 and 1.2 W/(m²K)).​​ In addition to adequate insulation, shading, usable thermal mass, natural ventilation and passive cooling possibilities are essential to minimise the energy demand of the buildings.

For the supply of the remaining energy demand for heating and cooling, highly efficient technologies using – if applicable – renewable energies should be installed. In the case study buildings, mainly heat pumps and district heating with low specific emissions are used – in several cases in combination with solar thermal. Boilers only play a minor role (see figure below). In addition and for the integration of renewable energies, in most buildings thermal storages are installed.

Concerning renewable energies, solar technologies and specifically PV are the dominant technologies used in the CRAVEzero frontrunner buildings (see figure below). Both​​ PV and solar thermal​​ are well developed and relatively easy to install on or at buildings.​​ They do and will play a major role in nZEBs as these buildings are only possible with the use of onsite renewable technologies.

A detailed description of the technologies installed in the CRAVEzero case study buildings can be found in the recently published Guideline II: nZEB Technologies available here.

Download the full report here:

NZEB Construction Market

The building sector in Europe is responsible for approximately 40% of the total energy consumption. The percentage accounted for residential buildings amounts at 27% of the total. Hence, this sector has a key role in the path towards the enhancement of energy efficiency and reduction of greenhouse emissions at EU level. The EPBD, together with the Energy Efficiency Directive and the Renewable Energy Directive, established a set of measures with the aim to provide in Europe the conditions for significant and long-term improvements in the energy performance of the construction market.

The EPBD established that, starting from 2021 (2019 for public buildings), all new buildings must be nZEB. On average, the volume of housing development across Europe amounts 2.8 completed apartments per 1000 citizens (Figure 1). The number of households, at European level, is expected to increase by more than 15% by 2050 compared to the number measured in 2013.

Figure 1: Number of completed dwellings per 1000 citizens (Deloitte, 2017).

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