B-18 Operational energy demand for new buildings – Boundaries and scenarios for simplified LCA

Aspect B-18 Operational energy demand for new buildings – Boundaries and scenarios for simplified LCA
Description
Several parameters can influence the results of the operational energy demand for the use stage of buildings, such as the selection of uses (i.e. building-related or non-building-related uses). European standards (EN 15804/EN 15978) recommend taking account of priority building-related uses such as heating and cooling. However, non-building-related appliances can significantly influence the energy needs of building-related uses (e.g. the thermal gain of appliances decrease the level of heating demand). How can this aspect can be addressed for in simplified LCA of new buildings?

related study objective

stand-alone LCA comparative assertion

related study phase

goal and scope definition inventory analysis (LCI) impact assessment (LCIA) interpretation reporting

relevant for

new buildings existing buildings construction products screening LCA simplified LCA complete LCA
Provisions For simplified LCA of new buildings, every building-integrated system should be accounted for (including building-related uses as described in the EPBD and other building-integrated systems). Non-building-related systems may be also accounted for, considering a conventional or statistical scenario.
Rules from:
EN 15978:
7.4.4.7 Boundaries for operational energy use
8.6.5 Scenarios for operational energy use – Module B6
Guidance
Building-related uses are defined according to the Energy Performance of Buildings Directive (2002/91/EC). Energy demand for building-related uses (heating, cooling and air conditioning, ventilation, heating for provision of domestic hot water, lightning) should be calculated either according to national calculation tools and methodology or with the help of thermal dynamic simulation. For comparative assertions the ‘EPA-NR’ calculation tool and methodology can also be used in order to calculate the energy demand on a consistent basis.Building-integrated systems refer to any energy-consuming system required to achieve the expected building functions. They include internal transport (e.g. lifts, escalators), shutters, fire security devices, communication systems, etc.. The energy demand of building-integrated systems may be calculated according to statistical or conventional scenarios.Non-building-related uses include other energy uses such as plug-in appliances (e.g. computers, washing machines, refrigerators, audio, TV) and production- or process-related energy in the use of the building.Scenarios for the calculation of the energy consumption of building-integrated systems and non-building-related uses may reflect statistical or conventional user behaviour. For example, the type and number of appliances and the frequency of use should be calculated according to statistical data if no accurate data are available. The expected performances of user appliances may be taken into account within the calculation, if available (e.g. the consumption of a refrigerator may be estimated according to its certified efficiency).

When no information is available for non-building-related uses, the ratio of consumption provided in EN 15603:2008 (Annex C) may be used.

Link between energy consumption values and environmental impacts

Once the energy consumption values are calculated, they need to be associated with generic or specific LCA data for the corresponding process. For example, the number of kWh of electricity in a French building project should be associated with the generic LCA data representing the average mix for the French context.

Other energy sources such as fuel, natural gas, wood and district heating also need a generic LCA data describing only the combustion. To this purpose, the infrastructure (e.g. the boilers) should be accounted for as technical equipment. This equipment contributes to the embodied impacts of a building along with the building products.

Depending on the goal definition of the study (cf. aspect ‘Classifying the decision context between situation A from B from C’), it is possible to choose, e.g. for the electricity consumption, an average mix or a marginal mix. The marginal effects are usually modelled using consequential modelling (situation B according to the ILCD Handbook). A final option is to choose hourly LCA data, particularly in the case where the thermal simulation results are provided on an hourly basis. This remark is part of the EeBGuide aspect ‘Dynamic LCA data for assessing the impact of electricity consumption’).


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