DIRECTION Site Munich
The German demo site is located in the Munich, under a Continental Climate. The building, known as NU-office, has 11, 000 m² of floor space dedicated to offices and shops. The building is awarded with an international Platinum LEED certificate in Green Building, being a unique example in Europe as for a non-private housing.
Essential concept components are targeted on use of environmentally compatible building material, high quality of ambient air, maximum flexibility of occupancy and high energy efficiency for heating, cooling, ventilating and lightening.
NU Office building in Munich (Source: Project´s website)
- Energy efficient buildings - new buildings:
- Improved insulation of exterior walls, innovative systems engineering, optimized daylight concepts, triple glazing windows with high efficient framing, external and internal shading-systems, high efficient lighting using LED technology.
- Heat pump:
- Absorption heat pump, powered by district heat, where heat is extracted from ground water.
- District heating/cooling – DHC:
- Used in combination with absorption heat pump, in cooling periods groundwater is used for passive cooling.
- Mechanical ventilation and heat recovery:
- With semi-decentralized ventilation units that permit high heat recoveries, natural ventilation is also possible with openable windows in the whole building.
- On all roof areas.
Key technical Performance Indicators – results
As a result of the energy efficiency and RES interventions the thermal energy delivered decreases by 40 % while the electricity decreases by 9 % compared to the reference building as seen in Figure 1.
Figure 1: Final energy demand and consumption of reference, design and monitored building
Compared to the design data a reduction in final energy demand of 6 % can be achieved. In comparison with business-as-usual (reference building) the final energy savings amount to 31 % as seen in Figure 2.
Figure 2: Comparison final energy demand (reference and design) and final energy consumption (monitored)
Primary Energy and CO2-Emissions
For the assessment of primary energy requirements primary energy factors from the data collection sheets according to DIN V 18599:2012 are used. If not stated in neither data collection sheets nor project deliverables, desktop research is conducted and values from trustworthy sources used (see Figure 3). The planned primary energy of electricity is lower by one third compared to the monitored data. In comparison to the reference building 38 % of primary energy is saved.
Figure 3: Primary energy needed for reference, design and monitored building
CO2 factors from the Council Information System of Munich (RIS) are used for the calculation of CO2 emissions. As a result of interventions undertaken a total annual amount of 201.5 tonnes of CO2 (10.9 kgCO2/m²a) can be saved in comparison to the reference building. In relative numbers this is an emissions reduction of 60 %. The monitored CO2 emissions amount to 132.8 tonnes per year (7.17 kgCO2/m²a) (see Figure 4).
Figure 4: CO2 emissions of reference, design and monitored building
Key Financial indicators
The investment costs and energy prices are extracted from the provided deliverables and analysed as to their validity. The electricity price for the year 2014 in Munich is 0.21 €/kWh for private customers. The price used for the calculations and stated in the data collection sheets is 0.17 €/kWh. The energy price for light oil is 0.09 €/kWh. District heating costs 0.06 €/kWh. For the payback period calculation of the demonstration site a discount rate of 3 % and an inflation rate for the energy carriers of 3 % is assumed.
The investment costs associated with energy efficiency and RES interventions amount to 5,918,000 € and are distributed across the interventions.
Table 1: Distribution of investment costs across interventions
Energy savings and energy cost savings
The total energy savings compared to the reference building are 284 MWh per year. The respective energy cost savings are 29,581 € per year with the reference building as the baseline. Compared to the design the actual building’s annual energy costs are higher by 3,372 €. The distribution of the energy and energy cost savings across energy usage is shown in Table 2.
Table 2: Energy and energy cost savings of monitored building compared to design and reference building
Table 3: Payback period for designed and reference building as baseline
The total costs of the reference building are 20,529,882 € and those of the new building 21,005,000 €. With a cost difference of 475,118 € the payback period of the monitored building with the reference building as the baseline is 16.1 years as shown in Table 3. The costs saved due to energy efficiency measures concerned with space heating and cooling are three times as high as the costs saved because of lower electricity consumption. The payback period of the monitored building with the designed building as the baseline is 19.4 years.
The same value for investment costs is used for the designed and monitored building. The calculation of the payback period ignores the potential of altering the rent to account for the savings and other improvements. That is why the potential for a lower payback period exists and needs to be taken into account when replicated. Once this is factored, the payback period may fall into an acceptable range for building owners.
Owners are reluctant to invest because it’s the tenants who pay the energy bills, while tenants don’t directly intervene in the building development phase as they don’t own the building.
A way of approaching this problem is by showing energy efficiency benefits can trigger owner demand. Energy efficient solutions need to be demonstrated to building companies and owners so that they can understand the advantages brought about, and how investment costs can be offset by later earnings. The Nu-Office implemented several energy saving measures that were able to predict energy consumption below the average office building consumption, thus offering tenants a “flat-rate charge” on consumption costs and generating a marketing advantage for the building.DIRECTION Project Best Practices Book, DIRECTION Site Munich