After refurbishment, heat recovery and demand control of the air flow were installed and the use of the systems were optimized.

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1 Property name: Nordstan Nordstan Objekt 6 Property owner: Vasakronan AB Consultants: GICON Total Concept method Step 1. Creating the action package Building and its use Year built: 1968 Area: m² Heated area Type of building: Office and shops The property Nordstaden 8:27 is commonly named Nordstan Objekt 6 and is situated in the central part of Gothenburg. The building is owned by Vasakronan AB and the total heated area of the building is m 2. It was originally built as a bank office. Since then, the building has been renovated several times and now hosts offices and warehouses. About 50 % of the area is office space and 46 % is shops. The building was latest refurbished in Indoor climate I After refurbishment, heat recovery and demand control of the air flow were installed and the use of the systems were optimized. The status of the building and its technical systems before measures I Building envelope In the pilot project in Nordstan Objekt 6 none of the energy saving measures were related to the building envelop. Heating The main part of heating is done with district heating. A heat pump with a yearly average COP of 4 was installed in the refurbishment. 1 (5)

2 Ventilation 2016 The ventilation system consists of twelve air handling units and it is a large building with complex systems. The systems had been rebuilt and extended in many different steps since 1968 and the documentation had not been updated. Recirculation fans were installed and the excess heat from cooling processes were recovered for heating. Some of the systems were separated in order to optimize the operation. It is still the original air handling unit from 1968 that operates. Cooling The cooling is done with both district cooling and cooling with outdoor air. Control and monitoring system(s) The original monitoring system made in 1996 is still used. Energy and resource use before measures (2009) Specific energy use before measures Whereas Heat energy Electricity for building operation District cooling 167 kwh/m²,year 57 kwh/m²,year 52 kwh/m²,year 62 kwh/m²,year The building initially used about 167 kwh/m 2, yr not included tenant s electricity. No baseline were set. Identified energy saving measures I 2 (5)

3 1.1 New air handling unit with new cooling treatment One (L66) of the twelve units serve location in the whole building. This is replaced with a new one with heat/cooling treatment to use excess energy in the building and connected with free cooling and with demand control. 1.2 Optimization air treatment unit with recirculation The operation of two air treatment units (L64 and L65) will be optimized and get new recirculation fans. 1.3 Installation of new heat pump During winter the building have both cooling and heat demand. New heat pump of 210 kw will transfer excess heat to the radiators. 1.4 Installation of heat recovery The heat from a cooling unit in a restaurant will be recovered in the heating system. 2.1 Adjustment/renovation of three air handling units serving shops The shops have different needs, the food shop have a heating demand while other shops have a large cooling demand. Install control for variable airflow in the supply and exhaust channels and time control. Prepare for free cooling with cold outdoor air in winter time and reduce airflow. CO2 control of ventilation. 2.2 Optimization of cooling circuit The house has large cooling demand due to large internal heat loads including from data centers and dense furnishing. The system have a constant flow through the two main pumps. The measure is to optimize the pumps in the system with pressure control to run variable flow in the circuit. Pumps will be shut down when free cooling is used wintertime. 2.3 Remove reheat coils Three air handling systems have reheat coils in the air handling system with high pressure drops and are not in operation and have no function. These will be removed and adjustments on airflow will be made. 2.4 Demand control of ventilation in offices Ventilation units for offices are provided with demand control through temperature compensation and time control. 2.5 Night cooling Function for night cooling exist but is not used. The function is modified and implemented and now include recirculation. 3 (5)

4 Summary of the measures in the action package Measure Optimization air treatment unit with recirculation Optimization of pump operation in the cooling circuit Invesment cost ksek Cost saving ksek/year Demand control of the air flow in offices Installation of heat recovery Night cooling in the circulation air and an air treatment unit Adjustments/renovation of three air handling units Remove reheat coils in three air treatment units Installation of heat pump New air handling unit with new cooling treatment Design and project management Sum: The costs do not include taxes. Energy saving MWh/year 4 (5)

5 Energy use [kwh/m2] heat cooling building electricty before package 1 (measure ) package 2 (measure ) Results The implementation of the energy saving measures was done in three phases, with three packages of measures, where the first two packages have been implemented. The total energy use of the building after the refurbishment (package 1 and 2) is 93 kwh/m2 and year and include 17 kwh/m2, yr for district heating, 40 kwh/m2, yr for cooling and 36 kwh/m2, yr for building electricity (December 2015). The aim for the two first phases was to achieve a total energy use of 84 kwh/m2, yr and the electricity use was not reduced as calculated. However, with a third package the consultant and the property owner believe that they can come down to a total energy use of about kwh/m2 in year (5)