The BaU scheme was a traditionally designed office building with a steel frame and a concrete slab, a large basement beneath both buildings and gas fired heating system.
It also reduces the number of people onsite, increases safety as a result of reduced work at height, lowers capital costs and improves construction speed.. Passivhaus and net zero carbon challenges.There is an increasing amount of pressure growing in the construction industry to design net zero carbon buildings, both in terms of operational and embodied carbon.
In this context, bodies such as the London Energy Transformation Initiative (LETI), RIBA, GLA and UKGBC, have developed guidance documents on embodied carbon, which include specific targets and roadmaps to achieving net zero carbon prior to 2050.. Based on LETI Climate Emergency Design Guide, a typical medium size residential building embodied carbon, would be 33% of the total carbon, whilst the operational carbon would be around 67%.However, for an ultra-low energy building, like Passivhaus, the breakdown would be 77% embodied and 23% operational and this balance is likely to become more enhanced with the decarbonisation of the grid.This means that embodied carbon is becoming a more important focus for the sustainable design of buildings..
Typical operational and embodied carbon breakdown for medium scale residential for a standard building (left) and for an ultra-low energy building.Passivhaus standard has always been focused on operational energy, and it is only in recent years that the focus has grown to both operational carbon emissions and the embodied carbon within the building..
Operational carbon in sustainable building design.
From an operational carbon perspective, Passivhaus’ low energy targets mean the dwellings are likely to achieve very low carbon emissions.Using expected market demand as well as the ongoing truss system designs, a process flow for fabrication was developed with initial layouts for arrangement and quantities of equipment.
Most of this process is to be automated with some manual intervention for transport, quality assurance and painting; processes where automated stations are unnecessary or significantly expensive against provided benefit.. To provide a better understanding of the system, we built a time-based discrete event model to represent the process and provide key outputs for various sets of input parameters.This allows the designers and stakeholders at an initial planning stage to see, digitally, how their assets could perform during production and provide feedback during the project at the earliest opportunities where large changes can be made to maximise value.. For the purposes of this project, operations upstream of raw material addition, and operations downstream of the final truss painting, were excluded from the simulation.
The remaining process steps represented the core fabrication steps to transform raw materials into finished trusses, in addition to some of the largest investments in capital and automation and, therefore, the areas of highest interest.. We built the model itself in AnyLogic, primarily with the process modelling and material handling libraries.We drew a spatial representation of the factory to define the arrangement, quantity and sizing of process stations and travel routes (including conveyors and forklifts) as well as crane zones to facilitate movement of raw materials and assemblies through parts of the line.