7. Passivhus Norden Sustainable Cities and Buildings. Cost-energy analyses of measures, upgrading an office building to passive house level in Norway

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1 Copenhagen, August Passivhus Norden Sustainable Cities and Buildings Brings practitioners and researchers together Cost-energy analyses of measures, upgrading an office building to passive house level in Norway Anna Svensson 1*, Anders-Johan Almås 1, Mads Mysen 1 1 SINTEF Building & Infrastructure, Norway * Corresponding anna.svensson@sintef.no / ans@erichsen-horgen.no SUMMARY Most existing non-residential buildings have a potential to reduce energy use in a profitable way. However, showing the profitability of the considerable investment involved in an upgrade to passive house level, can be demanding to sell in to the top management and decision makers. A method called Total Concept is applied when evaluating energy efficiency measures complying with the terms of the property owner in regards to the internal rate of return. A pilot building is chosen; evaluating the profitability of upgrading the building to Norwegian passive house level instead of the current building code. Only four of the single measures satisfy the requirements of the property owner, but five of the six identified measures satisfy the requirement when considering them as a whole action package. KEYWORDS Energy ambitious upgrading, Passive house, LCC, Retrofitting, Energy measures INTRODUCTION Around 80 % of the existing Norwegian building stock will still be standing in year 2050 (Flæte O.,2012), hence renovation of buildings has a high potential of energy efficiency and profitability. The measures that significantly reduce the energy need often entail considerable investments and if the measures are to be carried out they have to align with the property owner s expectations of long term investments. Until now, very little support is offered to the building owners regarding how to make the best decisions of investment in order to improve the energy performance of their buildings and reduce running costs. The decisions are often based on the profitability of single measures, and the feasibility is commonly evaluated with simple financial methods, e.g. simple payback method, which does not take into account the life time of the total investment and technical systems and rarely the future changes in energy prices. With this approach there is a great risk that only the simple measures, the low hanging fruit, will be carried out while a number of other possible measures with great energy saving potential will be overlooked. In order to overcome this obvious risk, a method called the Total Concept is used. The basic idea with the Total Concept method is to form and implement a package of energy saving measures that together fulfil the profitability requirement set by the building owner. In the method, the most financially profitable measures will assist the less profitable measures. The Total Concept method use a systematic approach throughout the whole building process of the energy retrofit, and includes both quality assurance of the process as well as a way of presentation of financial facts that provide guidance for the decission making. (Total Concept, 2014). This paper presents the experiences from a pilot study of an office building in Norway with a high energy ambition corresponding with the Norwegian passive house standard (NS 3701:2012). By comparing measures from building code level to passive house level, the method will show the total profit of upgrading the building components to passive house level instead of building code level. Page 1/8

2 The Total Concept method includes the economic realities a building owner has to take into account, and at the same time increase the ambition and makes it possible to achieve greater energy savings compared with traditional methods. Currently, the method is being tried out in Sweden, Denmark, Finland, Estonia and Norway. METHODS A method called the Total Concept method developed in the project "Total Concept method for major reduction of energy use in non-residential buildings" (EU- project IEE/13/613/S ) is used as basis for this case. The basic idea with the Total Concept method is to identify an action package of energy efficiency measures that together fulfil the profitability frames set by the property owner, by calculating the Internal Rate of Return (IRR). The most profitable measures will assist the less profitable measures. For the package of measures, the different life times of the measures and their combined impact on energy saving is considered over the total economical lifetime of the building. The change of energy price during the lifetime has a great impact on the profitability. The method enables therefore a percentual change in the energy price. The baseline for the existing building is defined as the energy use relevant to compare with the energy use after the refurbishment. Deciding a baseline can be complex, enabling the ability to: 1. Compare energy use before and after. 2. Decide which costs that should be included for the measure and which cost should be delegated to maintenance cost. The chosen baseline for the "existing building" in this case is called an adjusted dynamic baseline (Mysen M. et al.), considering profitability of investments and savings of a measure up to passive house level in proportion to a level required by the Norwegian building code (requirements of the existing building code). Accordingly, energy savings and investment cost for energy efficiency measure only takes into account the difference between current building code level and passive house level. If the existing building has a problem with the indoor climate and new ventilation system is required, the baseline will be set already with new ventilation, according to the current building code (TEK10). THE PILOT BUILDING The Norwegian pilot study building is owned by Statsbygg, a Norwegian public real estate owner, and the tenants are the Public Roads Administration. The buildings consist of three wings built in different building phases; 1967, 1976 and The original part is a one-floor building including a control hall and the northeastern wing with three floors. The southwest wing was built in 1967 originally with three floors, but was expanded with two floors in 1984 (figure 1). The building mainly consists of offices for the Public Roads Administration and canteen in the first floor. One part of the building is a control hall, but this will not be included in further evaluations. The heated floor area of the part of the building, which will be evaluated further, is 4330 m 2. N Figure 1: Floor plan over the 2. floor for the southwest and northeast wing. Page 2/8

3 Building envelope The building main load-bearing structure is of concrete with beams, columns and walls as primary building components. The facades are of 150 mm thick concrete, internally insulated with 100 mm and have a U-value of 0.41 W/m 2 K. Some concrete columns are located in the facade and create large thermal bridges. The air tightness is not measured but estimated to 3.5 h -1. There are large horizontal window bands in the concrete walls. The windows are original coupled windows with an average U- value of 2.4 W/m 2 K. All wings have a flat roof with 150 mm insulation over 150 mm concrete. The roofs have a U-value of 0.23 W/m 2 K, except over technical rooms with a U-value of 0.33 W/m 2 K. The floor is a concrete slab and has an estimated insulation of 100 mm with an equivalent U-value of 0.15 W/m 2 K. Building service systems The building has two oil boilers á 350 kw and one electric boiler of 225 kw. The boilers cover space heating, heating coil for ventilation and domestic hot water. The electric boiler is prioritized and constitutes 99% of the heating. The space heating is distributed through a conventional radiator system and hydronic heating coil to ventilation (80/60 C). The extension of the west wing (4th-5th. floor) has electric heaters. The building has six ventilation units in total, whereas two of them are from 1976 and in poor condition. These two also have a low heat recovery rate of 42 and 62%. The units have an average SFP of 3.7 kw/(m³/s). The buildings are air-conditioned and have a cooling system consisting of a chilled water plant from The latter covers comfort cooling via chilled beams in the 2nd floor, as well as comfort cooling via ventilation, for the entire building. The eastern wing is air-conditioned via the ventilation system and locally placed direct expansion units (DX). Process cooling of server rooms, telecommunication center, waste areas and UPS room is provided by smaller local DX units at the room / installations, respectively. There are altogether 15 cooling units in the building. The DX-units have a total capacity of 119 kw and the chilled water plant at 100 kw. The building has mainly office space, with T5 and T8 lighting fixtures in the offices and corridors. The internal loads have not been measured, the estimated required power used in the energy calculation is 8 W/m 2 and for equipment 11 W/m2. The internal heat gain for people is estimated to 4 W/m 2. Energy use Statsbygg has documented measured energy use for the entire building for the last 10 years. The energy report for 2013 shows the total measured delivered energy, degree days corrected and corrected operating hours for the entire building including the control hall. Total heating is 79 kwh/m 2 for the whole building, whereas 99% is electricity and only 1% oil. Total delivered energy from electricity, excluding heating, is 140 kwh / m 2. The energy use, which will be used further as baseline is the estimated total energy for the building's office section, excluding the control hall. Table 1. Calculated energy use in the existing building which will be refurbished Energy use Total Heating Tenants Delivered energy [kwh/m²year] 193,9 99,4 60,7 DRIVING FORCES, AMBITIONS AND REQUIREMENTS The building is almost 50 years old and is in need of a refurbishment due to poor indoor climate, especially in the parts with the oldest ventilation systems. The tenants was in a phase of renewing the contract and demanded a refurbishment. The company was also expanding and required more office space, thus a new wing was needed. The property owner had an ambition to reach passive house level and also wanted to convince the tenants to agree to this. The Norwegian regulatory requirement for existing buildings is interpret as Page 3/8

4 follows "A measure on a building component on an existing building, must satisfy the minimum requirement in the current building code". When evaluating the measures with the Total Concept method, the total action package for the refurbishment should satisfy the property owners IRR requirement of 4.15%. It is further estimated a relative increase of energy prices by 2% above inflation and economic lifetime of the building is set to 60 years. IDENTIFIED ENERGY SAVING MEASURES Six major energy efficiency measures are defined for the Road Office in Steinkjer. The measures are defined as energy savings and investment costs from building code requirements to passive house level. An action package is to be formed by the measures. Table 2. Identified energy measures being evaluated Nr Measure on building component 1 Windows and doors 2 Roof - add insulation 3 Artficial lighting 4 Ventilation - from CAV to DCV 5 Walls - add insulation and air tightness 6 Heat pump - air to energy well Energy simulation is performed for the existing building, for energy efficiency measures up to the building code requirement and up to passive house level. The most profitable measure is selected as the first action. Furthermore, a new energy simulation is made with a new ranking of the remaining measures, measure 2 is selected and a new energy simulation is made, etc. RESULTS Energy calculations and LCC-analysis are made according to the Total Concept method and the measures are ranked after profitability (table 3). The most profitable measure is selected as the first action. Furthermore, a new energy calculation with new ranking of remaining measures is made, measure 2 is selected and a new energy calculation with a new ranking of the remaining actions is performed, etc. Table 3. Life time, delivered energy for existing, TEK10 and passive house level and investment difference between TEK10 and PH, IRR for every separate measure. Measure Life time [year] Existing [kwh/m²yr] TEK10 [kwh/m²yr] PH [kwh/m²yr] Energy saving [MWh/yr] Investment TEK10 to PH [NOK] Windows and doors ,9 165,9 156,9 39, ,0 Walls insulation and air tightness ,9 193,9 189,3 136, ,7 Roof - add insulation ,9 186,5 153,6 7, ,2 Artficial lighting ,9 189,8 188,1 19, ,6 Ventilation - from CAV to DCV ,9 191,5 157,2 148, ,4 Heat pump - air to energy well ,9 138,6 134,5 17, ,7 IRR [%] Page 4/8

5 Figure 2: Fictional picture of the profit of all the separate measures, shown in the tool, provided through the Total Concept method The most profitable measure for the Road Office building is to replace all the windows and doors. The existing, will be replaced with passive house windows and doors, with an average U-value of 0,8 W/m²K instead of TEK10 windows with an average U-value of 1,2 W/m²K. The lifetime of windows is estimated to 30 years, the investment to NOK and the energy savings to kwh/year. The IRR for this measure is 34%. The roof is a flat roof and adding insulation have is a relatively low investment cost and is assessed as a profitable measure in the calculations. The lifetime of the roof is estimated to 40 years. The investment is estimated to kr from TEK10 to passive house level and the energy savings to kwh/year. This second most profitable measure has an IRR of 9.5%. When replacing the usual traditional lighting to LED lighting the energy use for lighting is reduced with 50%, though such measure decreases the heat gain from the lighting and increases the heating demand, hence the energy savings for the building are: Energy Saving Lighting Increased Heat Demand = Total Energy saving 54,6 MWh 26,9 MWh = 27, 7 MWh [ ] [ ] [ ] The investment also includes reduced maintenance needs, with fewer shifts of light bulbs. This is estimated to 5000 NOK / per year. The lifetime of lighting is estimated at 15 years. The investment is estimated to kr and energy savings are kwh/year. The IRR of the measure, as measure nr. 3 in the action package, is 8.3%. Demand controlled ventilation adjusts airflow by the presence in the offices, if there is a low occupancy, there is a low air flow and when it is high occupancy is full airflows. Also when the office is used outside the operating time, the ventilation system regulates, such as a low air flow can be used in the unoccupied parts of the building, instead of having full air flow with CAV. By replacing the CAV system in the building to demand controlled ventilation the average airflow for the building can be reduced from 10 to 6 (m³ / h) / m² in the operating time and from 3 to 1 (m³ / h) / m² outside the operating time. This increases the efficiency of the heat recovery by 3% and reduces the SFP from Page 5/8

6 to 1.5 kw / (m³/s). The lifetime of the unit is estimated to 15 years with an additional investment of NOK and energy savings of kwh/year. The IRR of the measure as measure nr. 4 in the action package is 5.57%. The planned insulation of the exterior walls also improve the air tightness and thermal bridges and is included in the measure. The lifetime of the outer wall is estimated at 40 years. The investment is stipulated to NOK and energy savings to kwh/year. The internal rate of the measure as measure nr. 5 in the action package is negative, -5.6%. The energy supply for the existing building is two oil boilers and one electric boiler. The measure satisfying TEK10-level, replaces the boilers with an air-water heat pump. A major investment which can provide a greater energy savings in a cold climate is a ground source heat pump, which is chosen as the alternative for passive house level. The lifetime of the heat pumps is estimated to 15 years with an additional investment of 1.4 million NOK, for the ground source heat pump, and an energy saving of kwh/year. The energy savings has been reduced in line with that implementation of the 5 measures above. The IRR for the measure as measure nr. 6 is negative: -18%. Four of the measures manage the 4,15% IRR requirement if you look at the measures one by one, however, looking at the whole action package five of the six identified measures satisfy the requirement of IRR from the property owner, figure 1. The chosen action package with five measures reduces the delivered energy from building code to passive house level with kwh/year, 47.4 kwh/m²year. The total energy savings from existing building to passive level is kwh/year, 91,2 kwh/m 2 year. The action package total investment cost from TEK10 to passive house level is 2 TCrank Investment IRR Measure [knok] [%] 1 Windows and doors 109,6 34, ,1 34, NOK and gives an IRR of 4.2%, see table 4. Table 3. Ranked measures with individual and total IRR Energy savings [MWh/year] Total saving [knok] 2 Roof - add insulation 58,7 9,5 5,2 4,68 25,6 3 Artficial lighting 286 8,3 27,7 29,93 16,3 4 Ventilation - from CAV to DCV ,6 129,5 116,55 9,3 5 Walls insulation and air tightness ,6 3,9 3,51 4,2 - Heat pump - air to ground source ,5 5,85 0,8 Sum IRR [%] Page 6/8

7 Figure 3: The action package, shown in the tool, provided through the Total Concept method The property owner and the tenants agreed to go through with this action package of five measures. The oil boiler should also be replaced (KRD, 2012) and the property owner, did choose to invest in a ground source heat pump, although the investment won t be profitable. DISCUSSION The ranking of the measures play a considerable part in the profitability, for example the building components of the building envelope, insulating the walls or the roof, saves the same kwh. In the case choosing the heat pump before the "passive" measures in the building envelope, resulting in reducing the delivered energy before the net energy demand, would make the measures on the building envelope much less profitable. In this case the heat pump is placed as the last measure, also affected negatively by the previous measures on the building envelope, from -14,7 to -18 % IRR. Some input, as the air tightness is estimated, consequently the energy saving for such a measure is uncertain. The air tightness is also improved both by adding wall insulation and changing the windows. Due to the uncertainty, this could be put as an own measure and be shown in the graph as a variation of energy saving. The profit of changing the lighting actually becomes more and more profitable, the more measures been applied on the building envelope and the energy demand reduces. This can be explained by; the uncontrolled added heat from the lighting becoming more unwanted in a building with low energy demand. Deciding the predicted change of energy prices can be difficult. We have predicted an increase of the energy price, though the energy price actually has decreased the last 10 years. A possibility is to show the results with a variation of energy prices, to see the outcome of profitability. Using the adjusted baseline, showing the profit deviation on the measures, from current building code up to passive house level, is a way of showing that energy ambitious upgrading actually are profitable, or non-profitable. The total cost of the renovation is not included in this calculation and will therefore not be shown in the results. The purpose neglecting the total cost, is persuading the property owner; when doing a measure or a total renovation, considering putting in the "little extra", resulting in a better building and a more profitable renovation. When a building will be used for 60 more years, renovating up to an ambitious level can both be profitable for the property owner, be an advantage for in the real estate market, but is also in line with the national energy goals (KRD 2012). Choosing upgrading the building to passive house level is still a larger cost than to current building code, so the financing must be in place, but also the ambition. The property owner had an ambition to reach passive house level and were therefore less sceptical. The norwegian property owners stands out, in relation to other countriesin this concern, thus the property owners actually wants and demand a higher level when renovating (Levin 2015 & Haavik 2014). Page 7/8

8 For more sceptical property owners, being able to show the graph and the way of thinking with the Total Concept method, is a good communication tool to bring into the discussion between energy consultants/facility managers and the decision makers. If the financing is not in place for the whole upgrading, using the Total Tool as an step-to-step renovation can also be more profitable and sustainable, instead of reaching an unambitious renovation level, which consequently will lead to unprofitable additional energy renovations later. Calculating the profitability from the current building code to passive house level is not suitable for all buildings. The actual condition of the building, for example fragility of the facade and the ability to add insulation must always come into consideration, as well as cultural heritage. The ambition level must be realistic for the chosen building. CONCLUSIONS Although, only four of the measures manage the 4,15% IRR requirement, five of the six identified measures satisfy the requirement of IRR for the property owner when considering them as a whole action package. Seeing the measures as one action package more measures comply the terms and conditions for long-term investment from the property owner. In this case the property owner decided to undergo all measures. The ranking of the measure is critical for the IRR of the separate measures. When studying a building and evaluating the measures, the correlation between the measures must be taken into consideration, especially, when ranking a new energy source e.g. heat pump before passive measures, when parts of the building envelope are in need of renovation. The Total Tool Concept can also be used in building not achieving passive house level, but the ability to evaluate the measure against each other and then in an action package, can be useful in all existing buildings in need of renovation. The Total Tool is also a communication tool when two disciplines, the energy consultant/facility manager and the property owner/economists discuss possible profitable measures for maintenance renovation. If the financing is not in place for the whole upgrading, using the Total Tool as an step-to-step renovation can also be more profitable and sustainable, instead of reaching an unambitious renovation level, which consequently will lead to unprofitable additional energy renovations later. ACKNOWLEDGEMENT This work is a part of the project "Total Concept method for major reduction of energy use in nonresidential buildings" (EU- project IEE/13/613/S ), funded by EU and Enova SF. Enova was established in 2001 in order to drive forward the changeover to more environmentally friendly consumption and generation of energy in Norway. REFERENCES Flæte O. et al, NOU 2010:10 Tilpassing til eit klima i endring, KRD, ISSN Aurskog AS Haavik T. et al Upgrading of the non-residential building stock towards nzeb standard. SHC Task 47, Free download at project website: Levin P (ed.), Energy Renovations of Non-residential Buildings in Northern European Countries, Report on National non-technical Barriers and Methods to overcome them. Total Concept report D2.5, October Free download at project website: KRD 2012, Gode bygg for eit betre samfunn, Kommunal og regionaldepartement Mysen M., Svensson A., Almås A-J Economical baselines for energy ambitious upgrading of non-residential buildings, Passivhus NordenTotal Concept, Norwegian Standard NS 3701 (2012), Criteria for passive houses and low energy buildings Non-residential buildings, Page 8/8