When different energy conserving measures are implemented for reducing energy use in buildings and the buildings are connected to district heating systems, it is important that an overall system analysis is made which takes into account the effects of total change of energy use due to the energy conserving measures.

The method applied in this thesis uses hourly production data for the different production units in the district heating system in Gävle, Sweden. The merit order of the different production units is dependent on the electricity spot market price. To calculate the merit order, hourly data for the electricity price is used. The marginal production unit can then be determined for each hour of the investigated year.

This thesis analyzes five different energy conserving measures in a multi-dwelling building regarding how they affect the marginal production units in the district heating system. For CO₂ emission evaluations, two different combinations of heat and electricity conserving measures are compared to installation of an exhaust air heat pump. This thesis also analyzes how the configuration of the electric meter affects the measured amount of self-consumed and produced excess electricity for a single-family house and for two multi-dwelling buildings of different sizes.

The results show that the use of electricity is the most important objective to consider. The increased use of electricity for operation of the heat pump contributes to an increase of global CO₂ emissions and the electricity produced by the solar photovoltaic installation contributes to a decrease of global CO₂ emissions.

The results also show that the configuration of the electric meter is important for the single-family house but negligible for the multi-dwelling buildings. The amount of produced excess electricity is high for all buildings, which means that the economic value of produced excess electricity is important for a profitable installation.

The traditional energy system as we know it today will change in the future. There is a worldwide concern about the global warming situation and there are different actions implemented to limit the consequences from, mainly, the use of fossil fuels.

In this thesis, multi-unit apartment buildings have been simulated according to how the global CO2 emissions change when different energy efficiency measures are implemented. The simulated buildings have also been used to investigate how the calculated energy efficiency of a building according to Swedish building regulations varies depending on which technology for heating is used in the building and if the building has a solar PV installation or solar thermal system. When the energy efficiency of a building is calculated accord-ing to Swedish building regulations, this thesis shows that heat pumps are a favored technology compared to district heating. Another result is that electric-ity use/production within the investigated district heating system is the most important factor to consider when minimizing global CO2 emissions.

This thesis also investigates how the configuration of electric meters owned by the distribution system operator affects the monitored amount of self-consumed and produced excess electricity. Finally, four local low-voltage distri-bution networks were simulated when a future charging scenario of electric vehicles was implemented.

If a single-family house installs a solar PV installation, this thesis reveals that the configuration of the electric meter is important for the monitored amount of self-consumed electricity. This thesis also shows that the investigated low-voltage distribution networks can handle future power demand from electric vehicles and a high share of solar PV installations, but rural low-volt-age distribution networks will need to be reinforced or rebuilt to manage the investigated future scenarios.

Sammanfattning Det traditionella energisystem som vi är vana vid idag kommer att förändras i framtiden. Oron för växthuseffekten och dess konsekvenser medför att olika åtgärder genomförs, framförallt för att minska koldioxidutsläppen från fossila bränslen.

I denna avhandling har flerfamiljshus simulerats med avseende på energi-användningen när olika energieffektiviseringsåtgärder implementeras. Resultatet av förändringarna i globala koldioxidutsläpp har sedan beräknats för de olika energieffektiviseringsåtgärderna. De simulerade resultaten har även använts för att analysera hur en byggnads energieffektivitet enligt Boverkets byggregler varierar med olika uppvärmningssätt och om byggnaden har en solvärme- eller solcellsanläggning installerad.

Denna avhandling visar att värmepumpar favoriseras jämfört med användning av fjärrvärme när en fastighets energieffektivitet beräknas enligt Boverkets byggregler. Samtidigt visas att den viktigaste åtgärden för att minska de globala koldioxidutsläppen är att minska elanvändningen eller att öka elproduktionen lokalt inom det studerade fjärrvärmeområdet.

Avhandlingen undersöker också hur konfigureringen av kundens elmätare i elnätet påverkar den uppmätta andelen egenanvänd och överproducerad el. Slutligen har fyra lokala lågvoltsnät simulerats då ett framtida scenario för laddning av elfordon adderats till fastigheternas nuvarande elanvändning.

Resultaten visar att om en villafastighet installerar en solcellsanläggning så påverkar konfigureringen av kundens elmätare den uppmätta andelen egenanvänd och överproducerad el och skillnaden kan vara relativt stor. Avhandlingen visar också att delar av lågvoltselnätet klarar en stor andel elfordon och en hög andel solcellsanläggningar men att landsbygdsnätet behöver förstärkas för att klara den ökade lasten i de antagna scenarierna.