Abstract

The ambition level for the zero emission neighbourhood Aadland is that the area will be self supplied with both thermal and electric energy. This paper presents how emissions from operation of the 500 dwellings are offset by on-site renewable energy production. The paper also describes a procedure for how to deal with embodied emissions from materials in an early stage design phase. The study verifies that it is possible to reach a zero emission balance for the neighbourhood. Zero emission from operation is achievable as an average for the neighbourhood. For individual zero emission buildings this also includes embodied emissions from materials and construction in a lifecycle perspective. Qualitative requirements for emissions from materials are defined for all buildings in the neighbourhood.

Abstract

The net-zero emissions building (nZEB) performance is investigated for building operation (EO) and embodied emissions in materials (EE) for Norway's cold climate. nZEB concepts for new residential and office buildings are conceived in order to understand the balance and implications between operational and embodied emissions over the building's life. The main drivers for the CO₂ equivalent (CO_2e) emissions are revealed for both building concepts through a detailed emissions calculation. The influence of the CO_2e factor for electricity is emphasized and it is shown to have significant impact on the temporal evolution of the overall CO_2e emissions balance. The results show that the criterion for zero emissions in operation is easily reached for both nZEB concepts (independent of the CO_2e factor considered). Embodied emissions are significant compared to operational emissions. It was found that an overall emissions balance including both operational and embodied energy is difficult to reach and would be unobtainable in a scenario of low carbon electricity from the grid. In this particular scenario, the net balance of emissions alone is nonetheless not a sufficient performance indicator for nZEB.

I ZEB, og som en del av arbeidspakke 5 "Konsepter og strategier for nullutslippsbygg", er det gjennomført en studie av to energikonsepter for boligområdet Ådland i Bergen.

Ådland ligger ved Flesland rett sør for Bergen sentrum. ByBo AS ønsker å bygge ut fra 500 – 800 boliger på området hvor både de enkelte boligene og området som helhet skal oppfylle kriterier for nullutslippsbygg.

I ZEB er det definert ulike ambisjonsnivå for nullutslippsbygg. Den gjennomførte studien anbefaler et ambisjonsnivå ZEB-O som et gjennomsnitt for Ådland området. ZEB-O betyr at området skal være selvforsynt med energi, inklusive elektrisitet og varme, over et år. I tillegg anbefales det at enkeltbygg skal oppfylle ambisjonsnivå ZEB-OM, det vil si at energiproduksjonen på bygget ikke bare tilsvarer det årlige behovet for energi, men hvor den fornybare energiproduksjonen også veier opp fra utslipp av CO2 knyttet til produksjon av byggematerialer. Det anbefales videre at det settes klare spesifikasjoner knyttet til materialbruk for hele området for å oppnå så lavt innhold av iboende CO2 fra materialbruk som praktisk mulig.

To alternative energikonsept er utredet for Ådland; naturlig klimatisering, en bygningskropp med varmetapstall tilsvarende passivhusnivå, solfangere for varmeproduksjon og solceller for elektrisitetsproduksjon er inkludert i begge alternativene. Begge alternativene omfatter også en energisentral som skal stå for hovedandelen av varmeproduksjonen og med et tilhørende nærvarmeanlegg for området. For alternativ 1 benyttes grunnvarmepumper for varmeproduksjon. All elektrisitetsproduksjon kommer fra solceller. For alternativ 2 benyttes en biogass drevet maskin som kombinerer produksjon av elektrisitet og varme (CHP).

Beregninger er utført for årlig energibehov og produksjon av varme og elektrisitet for begge alternativene. Analysen viser at det er mulig å oppnå en ZEB-O ambisjon som et gjennomsnitt for boligområdet Ådland for begge alternativene.

The paper aims to investigate whether it is possible to achieve a net Zero Emission Building (nZEB) by balancing emissions from the energy used for operation and embodied emissions from materials with those from on-site renewables in the cold climate of Norway. The residential nZEB concept is a so-called all-electric solution where essentially a well-insulated envelope is heated using a heat pump and where photovoltaic panels (PV) production is used to achieve the CO_2eq balance. In addition, the main drivers for the emissions are revealed through the CO_2eq calculation for a typical Norwegian, single-family house. This concept building provides a benchmark rather than an absolute optimum or an architectural expression of future nZEBs. The main result of this work shows that the criteria for zero emissions in operation (ZEB-O) is easily met, however, it was found that the only use of roof mounted PV production is critical to counterbalance emissions from both operation and materials (ZEB-OM). The results show that the single-family house has a net export to the electric grid with a need for import only during the coldest months. In the next stage of the work, the concept will be further optimised and the evaluation method improved.

In order to reach the goal of a zero emission building (ZEB), CO2 emission data has to be made available and verified for traditional building materials, new ‘state-of-the-art’ building materials and the active elements used to produce renewable energy. However, an initial literature review found that although there are databases of embodied carbon values for most building materials, the range in results for some materials are varied and inconsistent.

This paper follows on from previous work on the development of a transparent and robust method to calculate CO2eq emissions of the materials used in the concept analysis of the ZEB residential model, single family house. The aim of the concept analysis was to investigate if it was possible to achieve an "all-electric" ZEB-building by balancing operational and embodied emissions by PV-production on the building. The analysis has not considered minimising the embodied emissions but is rather a documentation of the embodied carbon dioxide emissions using traditional materials in the envelope and in the ventilation and heating systems, as well as, those associated with the renewable energy system, such as the photovoltaic panels and solar thermal collectors. Material inventories have been imported from the Revit BIM model, via MS Excel. The material inputs are structured according to the Norwegian table of building
elements, NS 3451-2009 and emission factors (kgCO2eq per functional unit) for the calculations are sourced from SIMAPRO/ Ecoinvent version 2.2.

The goal of these calculations is to estimate, and thus provide an overview of the materials and components in the ZEB residential model, which contribute the most to the embodied carbon dioxide emissions. The calculations are based on the principles of environmental assessment through life cycle analysis. It should be noted that in this first round of calculations, not all life cycle phases are included. In the next stage of the calculations, the model will be optimised and the impact on emissions recalculated accordingly

The building enclosure plays a relevant role in the management of the energy flows in buildings and in the exploitation of solar energy at a building scale. An optimized configuration of the façade can contribute to reduce the total energy demand of the building.

Traditionally, the search for the optimal façade configuration is obtained by analyzing the heating demand and/or the cooling demand only, while the implication of the façade configuration on artificial lighting energy demand is often not addressed.

A comprehensive approach (i.e. including heating, cooling and artificial lighting energy demand) is instead necessary to reduce the total energy need of the building and the optimization of the façade configuration becomes no longer straightforward, because non-linear relationships are often disclosed.

The paper presents a methodology and the results of the search for the optimal transparent percentage in a façade module for low energy office buildings. The investigation is carried out in a temperate oceanic climate, on the four main orientations, on three versions of the office building and with different HVAC system’s efficiency. The results show that, regardless of the orientations and of the façade area of the building, the optimal configuration is achieved when the transparent percentage is between 35% and 45% of the total façade module area. The highest difference between the optimal configuration and the worst one occurs in the north-exposed façade, while the south-exposed façade is the one that shows the smallest difference between the optimal and the worst configuration.

The main aim of the work has been to do modeling and calculations of the energy use, embodied emission and the total CO₂-emissions for a typical Norwegian office building. The goal is to find the most important parameters in the design of a zero emission office building, according to the current ZEB definition.

The main aim of the work has been to do modeling and calculations of the energy use, embodied emission and the total CO2-emission for a typical Norwegian residential building. By doing this we try to reveal and study the main drivers for the CO2-emission, and also which performance is necessary for components and solutions in a Zero Emission Building according to the current Norwegian ZEBdefinition.