Energy and climate on development sites (buildings)

The buildings in Stockholm Royal Seaport have been designed with a high performance building envelope and has through these passive measures achieved a good energy performance.

To achieve a high energy performance there must be well insulated facades, ceilings, floors, and windows, as well as energy efficient installations. In addition to a high-performance building envelope renewable energy will be produced locally on the roof of the buildings.

Energy calculations have been submitted during the buildings’ different design stages, the energy calculations are required to be updated and submitted for each phase. Once the building has been in operation for two years, metered energy consumption will be submitted, and the results can then be compared with the calculated values. Also, construction site sheds must be energy efficient, and all electricity used during construction has to be eco-labelled. Embodied emissions of built-in material should be minimized.

Energy performance per phase and property developer

Requirements:

  • Norra 2, Brofästet and Gasverket: housing units 55 kWh/m² and premises 45 kWh/m² purchased energy
  • Södra Värtan: housing units 50 kWh/m² and premises 45 kWh/m² net energy
  • Existing buildings in Gasverket: goal of 50% reduction
  • Norra 1 and Västra: voluntary commitments

All figures relate to the kWh/m²  Atemp year, and include energy for heating, domestic hot water, property energy, and cooling. Supplements for air circulation in miscellaneous rooms may be made in accordance with the Swedish National Board of Housing, Building and Planning instructions.

The results of the developers vary, but many of them achieved good results. Energy performance has gradually improved as the project progresses.

Map 3.1  Energy perfomance per phase and property developer
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Energy performance has gradually improved, at the same time, the requirements of the Swedish building code regulations, have tightened. However, only the purchased energy is reported.

In Norra 1 and Västra, the energy commitments were voluntary, and the developers’ data has not been reviewed by the city of Stockholm.

Diagram 3.4  Average energy performance per phase, kWh/m2 Atemp and year


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Norra 2 was the first phase that imposed strict energy requirements, with a weighting factor 2 for electric heating. All developments are connected to district heating and have a ventilation heat recovery system (air-handlings unit). Form factors, high-performance building envelope, and the proportion of windows/glassed surfaces vary between buildings.

Conditions that were less beneficial could be partially compensated by using technical components like solar panels, solar cells, and waste water heat exchangers. In this phase, it was possible to compensate with all self-generated energy. Differences of estimations of hot water due to a new Sveby-version (Swedish industry standard for energy) – 25 kWh/m2 Atemp – resulted in the need of compensating additional 5 kWh/m2 Atemp and year.  

Measued energy performance have been submitted by more than half of the developers. The city of Stockholm have reviewed the results, and it has been noticed that so far, no developer comply with the requirements. All developers report problems with metres and commissioning of systems, as well as heat losses, which, were not detected until the warranty inspection. Fine-tunings and adjustments of the systems are in progress, a reassessment will take place in a year.

Diagram 3.5  Energy performance Norra 2, kWh/m2 Atemp and year

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6 of 9 developers have, two years after occupation, reported metered energy performance values. So far, none of the properties comply with the requirements, and deviations have occurred because of measurement errors, and heating system problems (ventilation, thermal bridges, losses from warm water circulation, etc). Troubleshooting, measures, and adjustments will continue into 2019.

  • Bonava had a higher measured heat usage, a lower solar cell performance and a lower hot water use than expected.
  • Heba had higher hot water circulation-losses and higher air flow than calculated. A review of the heat recovery-performance, and adjustments of the heating system have been completed.
  • SSM had a higher heat use than calculated, and solar energy has not been metered. Follow-up procedures need to be improved.
  • Victor Hanson has accurately balanced and adjusted the heating system installations, and other systems such as solar collectors, finding errors in the installation of underfloor heating, measurement errors, etc.
  • Wallenstam (residential) have several errors in their heating systems, as well as a need to improve follow-up procedures.
  • Wallenstam (preschool) have a ventilation system that is not demand-controlled, and has high air flows, long operating times, and high indoor temperatures, this has resulted in a higher use of heating than calculated.
The following developers have only reported calculated values (occupancy less than 2 years):
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  • Erik Wallin has the lowest estimated annual energy performance, due to a credit of 9 kWh/m2 of locally produced energy.
  • Skanska has district heating, heat recovery, and solar cells.
  • Stockholmshem has district heating, heat recovery, exchangers, and solar cells, and there is a continuous work in collaboration with the contractor to achieve a good energy performance.

The change of requirements since Norra 2 means that it is no longer possible to compensate with self-generated energy in the energy calculation. In this development phase, a special land allocation competition for a plus energy building i.e. a house that produces more energy than it uses over the year, has been organized. 

The estimation for hot water use increased by 5 kWh/m2, year. Some developers chose to ensure their compliance with the requirements using a geothermal heat pump and/or installation of waste water heat exchangers, instead of optimizing the building envelope; despite a weighting factor 2 for electric heating. Greater focus has been put on hot water circulation and other system losses, and thermal bridges that have proven to be a very important part of the energy balance. Some developers have geo-heat recovery, with a preheating of the incoming air in the heat recovery. Half of Brofästet’s developers have an energy system combining geothermal heat pump, with district heating.

Diagram 3.6  Energy performance Brofästet, kWh/m2 Atemp and year

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  • The calculated energy performance of Stockholmshem’s plus energy buildings is 26 kWh/m2. The buildings have a good form factor, as well as construction and installation technical parameters with high performance, combined with minimized distribution losses. The solar cells system conversion efficiency is increased by the recovery of surplus heat from the inverters that reload the bore holes and optimize the geothermal heat pumps for domestic hot water production during the summer.
  • The calculated energy performance of Tobin Properties is 37 kWh/m2 using a geothermal heat pump with high performance, and heat recovery with geo-heat recovery solution, that preheats outside air, and cools the air in the summer.

Gasverket has several existing buildings with high cultural-historical values. The challenge has been to balance the historic values with energy efficiency measures. To reach the requirements, buildings are renovated with well insulated floor joists and roofs, as well as energy efficient windows and ventilation systems. New buildings are equipped with well-insulated building envelopes with heat recovery, and district heating.

Gasklockan 4 is designed with efficient geothermal heat pumps, district heating, and free cooling from the geothermal system. To minimize ventilation losses, each home will have on-demand ventilation The average u-value is under investigation, but it is uncertain whether it meets the requirement or not.

Diagram 3.7  Energy performance Gasverket and Gasklocka 4, kWh/m2 Atemp and year

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  • The Real Estate Office’s newly built sports Centre meets the passive house standard (according to FEBY – Swedish forum for energy-efficient buildings) with an energy efficient building envelope and a smart control ventilation system.
  • SISAB’s newly built school has been allowed to count high air extensions to compensate for a poor ventilation system.
  • Oscar Properties’ energy solution is based on efficient geothermal heat pumps with district heating, and free cooling from the geothermal system. The apartments are equipped with on-demand ventilation airflow units to minimize ventilation losses. The form factor is not optimal and the average u-value is under investigation, but it is uncertain if it meets the requirements.

In Södra Värtan even more strict energy requirements are imposed.
A land allocation competition has been organized and one of the selections criteria’s was to embrace lower energy performance, like 45 and 40 kWh/m2 Atemp net energy. Calculated design values are generally below the requirement levels, but these developments are still in early design stages. In Södra Värtan the focus will be efficient hot water circulation and minimizing other system losses. 

The requirements in Västra are based on voluntary agreements, the metered energy was reviewed by the city two years after move-in. The results are, by a wide margin, below the Swedish building code regulations, and are based on values corrected according to normal years.

Diagram 3.8  Energy performance Västra, kWh/m2 Atemp and year

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  • Einar Mattsson, Järntorget and ByggVesta have achieved good metered energy performance values due to heat recovery.
  • Svenska bostäder (Söderåsen); The high values are explained by a high hot water usage due to this being student housing, with more people living per unit area than in ordinary residential buildings.

The requirements in Norra 1 are based on voluntary agreements, and the metered energy performance was reviewed by the city two years after move-in. The results are, by a wide margin, below the Swedish building code regulations, and are based on values corrected according to normal years.

Diagram 3.9  Energy performance Norra 1, kWh/m2 Atemp and year
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  • Reinhold Gustafsson have geothermal heat, heat recovery, and rollback, with solar heat collected in water loops on the building’s green roof.

Local production of renewable energy per phase

Requirements:

  • On-site solar generation 2 kWh/m2of solar electricity or 6 kWh/m2 of solar thermal or a combination of these two. In Norra 2, the developers could choose to locally produce solar electricity at a minimum of 30% of the property electricity.
  • Norra 1 och Västra har frivilliga åtaganden.

All requirements are for kWh/m2 Atemp and year.

All property developers from phase Norra 2 and onwards have installed roof mounted solar to locally generate electricity or heat. Solar PV produce electricity and solar collectors produce heat. Most the property developers chose to install solar PV.

Map 3.2  Local production of solar energy per phase and property developer
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All new properties have installed solar and produce local renewable energy. Buildings in Norra 2 exceeded the solar requirements, the likely reason for this is that the developers were credited for this in the energy balance calculation. At later stages, the results are close to the requirements, except for the plus energy building of Stockholmshem in Brofästet, this building is exceeding the requirement.

Diagram 3.10  Local production of solar energy per phase, kWh/m2 Atemp and year

All developers achieved or exceeded the set requirement.

Diagram 3.11  Local production of renewable energy in Norra 2, kWh/m2 Atemp and year


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  • SSM has its solar installation on the roof of Bonava’s building, but due metering error the solar electricity production cannot be verified.
  • Erik Wallin and Viktor Hanson have PVs, as well as solar thermal collectors.
  • The renewable energy of Wallenstam comes from the newly-built wind turbines outside Stockholm.
Diagram 3.12 Local production of renewable energy in Brofästet, kWh/m2 Atemp and year

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  • Stockholmshem has installed solar cells to achieve plus energy buildings.
  • Åke Sundvall has received permission to place the solar cells of future projects in Gasverket East, as the building location is not suited for solar.
Diagram 3.13  Local production of renewable energy in Gasverket, kWh/m2 Atemp and year

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There are no solar panels on existing buildings in Gasverket, due to the historical value of the buildings. The solar electricity that SISAB’s school produce covers both new and already existing buildings.

Requirements in Västra are based on voluntary agreements. Four of the eleven properties have on-site solar power. HSB is the only developer in the stage that has reported a production of 2,5 kWh/m2 Atemp.

The requirements in Norra 1 are based on voluntary agreements. One developer, Reinhold Gustavsson, has local energy production, through a “ground heating system” on the roof.

Construction site sheds

Requirements:

  • For heating construction site sheds, energy sources with low primary energy factors are used, where possible. Electric heating is allowed if the need for purchased electricity is less than 4,000 kWh/year for an administration shed, or 5,000 kWh/year for a workers’ shed. The electricity used during construction should be eco-labelled.
  • In Norra 1 and Västra, there are no requirements. From Norra 2 and onwards, construction requirements have been met, and all property developers have electrically heated sheds that are energy efficient, only using eco-labelled electricity for construction.
Diagram 3.14  Measured energy use for construction site sheds in Norra 2

Comments:

  • Wallenstam’s housing and a pre-school shared construction site sheds.
  • HEBA, Skanska and Stockholmshem share site sheds and offices.
  • Erik Wallin, Wallenstam and Viktor Hanson do not have separate meters for their administration and workers sheds.

Embodied carbon and material

Requirements:

  • Climate calculation are to be performed before choosing the main building structure/ frame.

In the Stockholm Royal Seaport, the simplified model for life cycle analysis (LCA) developed by IVL has been tested by the developers. The city’s aim is to create an industry awareness of materials with high carbon footprints, and as to learn about comparability and, eventually, be able to specify requirements with key figures.

Energy and climate impact for public spaces

The vacuum waste collection system has been streamlined, energy efficient site sheds have been used. Eco-labelled electricity has been used for construction sites and site sheds. The embodied carbon calculations have been performed in order for the climate impact to be minimized at a later stage.

Vacuum waste collection system

Energy use in the vacuum waste collection station has been minimized by 30%, by optimizing the ventilation system. Energy use per ton of waste does not yet meet target levels, as the system is not fully developed yet, see table 3.1 below.

In 2017 and 2018, target levels for energy use for plastics and newspapers have declined. Energy use for residual waste has slightly increased because of leaking valves in the system. This issue has been resolved, and energy use should be reduced in the coming years. The leak affected the electricity use of the residual waste the most, since this is the largest waste fraction.

Table 3.3  Energy comsumption per tonnes waste from vacuum waste collection facility 
Tabell 1: Energianvändning per ton avfall från sopsug.
Target level / turn-outResidual wastePlasticNewspapers
Target level/ turn-outResidual wastePlasticPaper
Target level, kWh/ton 95³300110
Turn-out 2018, kWh/ton140349249
Turn-out 2017 kWh/ton 113401250

Construction energy use for site sheds, electricity and diesel usage

Stockholm City Environmental requirements regarding fuels, vehicles, machinery, management of chemical products, as well as materials and goods are implemented in the Royal Seaport.

The energy used in construction work is a small part of the total lifecycle energy. Fuel largely come from fossil fuel sources. All electricity is 100% renewable, and all diesels are of environmental class 1.

Table 3.4  Electricity and diesel usage during the building production, completed contractors kWh / m² detailed development plan.
Tabell 1: sammanställning av nyckeltal levande stad.
EtappNorra 2Norra 2BrofästetBrofästetGasverketGasverketGasklocka 3 och 4Gasklocka 3 och 4VästraVästraNorra 1Norra 1Jackproppen Jackproppen Ängsbotten Ängsbotten Totalt
Norra 2Norra 2BrofästetBrofästetGasverket västraGasverket västraGasklocka 3 och 4Gasklocka 3 och 4VästraVästraNorra 1Norra 1JackproppenJackproppenÄngsbottenÄngsbottenTotalt
StatusCompletedCompletedPlannedPlannedPlannedPlannedPlannedPlannedCompletedCompletedCompletedCompletedPlannedPlannedPlannedPlanned
DieselElectricityDieselElectricityDieselElectricityDieselElectricityDieselElectricityElectricityDieselDieselElectricityDieselElectricity
Demolition00000010,51,6IUIUIUIU3,50IUIU15,6
Remediation0,701,22,910,41,14,60,01IUIUIUIUN/AN/AIUIU20,9
Temporary site-access roads1,50,74,71,6N/AN/AN/AN/A55,50IUIUN/AN/A73,212,7149,9
Completion of public open space4,30,8h N/AN/AN/AN/AN/AN/A5,70,68,31,5N/AN/AN/AN/A21,2
Totalt6,51,55,94,510,41,115,11,6161,20,68,31,53,5073,212,7207,6
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Comments:

  • The energy use of the individual projects depend on the size of demolition and the size of the zoning plan.
  • Demolishing of the 90-meter-high Gasklocka 4 was extensive, and resulted in a high diesel and electricity use.
  • Two years of extensive soil remediation works were undertaken in Gasverket. The soil remediation of Gasklockan 3 and 4 was completed in November 2018.
  • Västra and Ängsbotten have high diesel use because of the poor ground conditions.
  • The high energy usage in  Norra 1 is because of large quantities of soil and rock that had to be excavated and moved.
  • The same contractor performed the completion of public open spaces in Nora 1, Västra and Norra 2 and could therefore utilise machinery more effectively across sites.

Climate calculation – embodied carbon for public spaces

To assess the embodied carbon from material and construction choices between the different stages, the city compiled the main material types and quantities, see the table below.

Soil conditions in Västra were unfavourable, and therefore required that piled decks were constructed. A piled deck consists of concrete and steel, which have a high impact on the climate.

Table 3.5 Climate impact of built-in materials per phase, public spaces
Tabell 1: Klimateffekter och inbyggd energi för etapperna, allmän platsmark
AspectAmount, unitNorra 1VästraNorra 2
AspectAmount, unit Norra 1VästraNorra 2
Amount of materialConcrete, tonnes15 20047 3562 705
Steel, tonnes1 0965 837358
Asphalt, tonnes3 3004 3943 347
Totalt, tonnes19 59657 5876 410
Tonnes/ m²2,687,681,28
Climate impact (tonnes CO2)Concrete, tonnes1 4304 455254
Steel, tonnes3201 704105
Asphalt, tonnes115153117
Totalt, tonnes1 8656 313476
Tonnes/ m²0,260,840,10

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Key figures

  • Housing units, average measured energy use is 15% below the current BBR in
    Norra 2.
  • Phase Norra 2 produced 240 MWh solar energy per year.