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.

This report deals with how to define what a Zero Emission Building (ZEB) is with explanation and analysis of different parameters related to embodied emissions of CO₂ equivalents. The report can be used as a guidance tool on how to assess embodied emissions, and also on what parameters should be evaluated in such an assessment.

Different ambition levels for ZEBs may include life stages, operation, material, construction and end-of-life and can be documented according to EN 15978. Calculation procedures should include system boundaries, embodied emissions from materials, transport, the construction process and waste handling according to the ambition level. CO_{2 eq} emissions factors, service life estimates and payback scenarios for CO₂ emissions need to be considered.

The report does not contain one single clearly defined method, but rather a state-of-the-art summary on the different issues and refers to other relevant national and international work in the field of ZEB definitions. The issues presented here are in early stages of development and will need to be verified and further developed.

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.

The main definition of a Powerhouse is a building that shall produce at least the same amount of energy from on-site renewables as the energy used during construction, manufacturering of materials, renovation, demolition and operation exclusive energy used during manufacturering of equipment such as PCs, coffee machines etc. In addition the exported energy shall in average not have less quality than the imported energy. This implies that produced and exported electricity can offset corresponding amount of imported energy for both electricity and thermal purposes, while produced and exported thermal energy cannot offset imported electricity. The building shall also as a minimum fulfil all the requirements of the Passive House standard according to NS 3701.

The first Powerhouse renovation building will be built at the Kjørbo site in Bærum, and start of construction was in March (2013). For the Powerhouse Kjørbo project, PV panels will balance the energy needed during it’s lifetime. The two buildings will thus export more electricity than it will use for operation. A geothermal heat pump, in addition to waste heat from the data/server room, will cover the heating and cooling demand. There will be no export of thermal energy. In a broader environmental perspective, an aim of this project is also to achieve the classification “Outstanding” in the BREEAM-NOR environmental certification scheme.

The heated useful floor area of the two office buildings at Kjørbo, which will be renovated to plus-energy standard, is about 5.180 m2, distributed on 3 or 4 floors. Energy efficiency measures and materials with low embodied energy have been crucial for obtaining the energy goal. A very efficient ventilation concept has been developed.

Powerhouse Kjørbo is a ZEB pilot building, i.e. a pilot within the Research Centre on Zero Emission Buildings (www.zeb.no). Therefore an aim is also very low greenhouse gas emissions during the building’s lifetime.

Calculations indicate that the energy balance during the building’s lifetime, and within the defined definition, fulfils the goal of plus-energy.

The aim of the Norwegian research centre on Zero Emission Buildings(ZEB) is to develop competetive products and solutions of buildings with zero emission of greenhouse gases related to their production, operation and demolition.

However, to develope solutions and concepts for zero emission buildings it is first necessarry to develop a sound definition of ZEB (for single buildings, and also cluster of buildings). During the first 3 years of the centres running, significant work have been done to adress different issues related to the ZEB-definition, among them defining CO2 factors for various energy wares. Work done in the International Energy Agency (IEA), and European organisations in light of the revised Energy Perfomance Buidling Directive (EPBD) have been an important basis for the ZEB-defintion work. Experience from the design process of 7- 8 ZEB pilot building projects comprising approximately 100 000 m2 floor area has also been an important background for the agreed ZEB-definiton. The ZEB-definition consist of nine points

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