Case Study: Marks & Spencer Oxford Street Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... Case Study: Marks & Spencer Oxford Street Environmental Design Solutions Ltd

State of the art building simulation software... Copyright © 2010 EDSL www.edsl.net State of the art building simulation software...

M&S Oxford Street State of the art building simulation software... Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... The Brief: Calibrate a base model using metered consumption figures – “existing building” Apply changes required in the refurbishment brief to predict energy consumption – “proposed building”. M&S Oxford Street Information required to create base model: Drawings Constructions Usage patterns Internal gains – lighting, occupants, equipment Plant operation We were to use the information provided by the client to build up the base model, then tweak this through client collaboration and ensure the base model is as close as possible to metered data There were elements of the building operation which were known, for example the footfall had been measured, plant & store hours were known, etc. The calibration in line with metered data helped to ensure the elements which were less well known were modelled correctly. In broad terms, we needed the items listed in order to build up the model. We will look at more detailed requirements shortly.

State of the art building simulation software... Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... Considerations… Some aspects of operation will affect heating & cooling demands: escalators cooling effect to space from cold aisles plinth heating of refrigeration units small power, e.g. tills Some items will not: Some of these demands would be included into the simulation to allow for the heat gains to the space, in turn these will then affect the heating & cooling demands on the space as well as the associated fan & pumps energy consumption figures. Cold aisle spillage & low level heating was accounted for and dealt with appropriately. Some demands were input from measured data provided by the client and were added to the energy consumption figures post-simulation, for example lift power consumption. The consumption of the refrigeration units was calculated from data provided by refrigeration manufacturers. refrigeration compressor energy consumption, including cold rooms & freezer rooms lifts

State of the art building simulation software... Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... The table shows how the client wanted the information broken down Energy Sub-System SITE – Pantheon Marks & Spencer From results of Thermal Modelling for original building (kWh/m2/yr) ( C) From results of Thermal Modelling of the refurbished design (kWh/m2/yr) (D) Electricity Gas Heating & hot water - Cooling Fans and pumps Humidification Lighting Office empty Catering Gas Catering electricity Other electricity Computer room Total gas Total electricity Total Energy Detailed information is required for each field in order to accurately predict consumption for each sub-system. Benefit of this calibration is to ensure that each end use category can be shown to be behaving correctly, i.e. heating & cooling consumption is as expected, fans & pumps, lighting loads, domestic hot water, small power can all be compared with monitored data by the client to give them confidence the quality of the analysis, and thus confidence in future predictions.

State of the art building simulation software... Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... Indication of detail required Heating & cooling efficiencies Distribution losses Pipe index circuit length & pressure drop Fan SFPs Hot water consumption, generator efficiency & distribution losses Lighting installed density Daily opening hours with hours of plant operation In order to effectively model the plant, we need information about each of the components as well as full details of what’s happening in each zone within the building. Method of heating, cooling & ventilation Ventilation rates

State of the art building simulation software... Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... Services Summary CAV heating & cooling Poor heating & cooling efficiencies – 65%, COP of 2.5 No heat recovery Supply Fan SFP = 3W/l/s, Extract Fan SFP = 1W/l/s Lighting 40W/m2 sales floor, 36W/m2 back of house 1.2l/s/m2 Fresh Air, 10 l/s/m2 total supply The existing building was very inefficient, with high electrical consumption through poor fans, lighting and cooling, and high gas consumption due to the inefficient boiler.

State of the art building simulation software... Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... Typical services schematic The heating, cooling & ventilation system used in the building was a CAV – Constant Air Volume system – with around 10% fresh air

State of the art building simulation software... Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... Typical services schematic A fair amount of heat was delivered to the space due to the operation of the fans. Clearly, reducing the amount of heat generated by the fans and thus delivered to the space will reduce energy intensive cooling demands.

State of the art building simulation software... Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... The refurbishment of the building had already commenced by the time we were approached, so availability of data was limited Energy Sub-System SITE - Pantheon Thermal Modelling on existing building (kWh/m2/yr) Metered Results (kWh/m2/yr) Electricity Gas Heating & hot water - 112.65 Cooling 84.8 Fans and pumps 123.97 Humidification Lighting 126.38 Office empty Catering Gas Catering electricity 20.7 Other electricity 66.56 Computer room Total gas 184.75 Total electricity 422.42 339.74 Total Energy 535.06 524.49 With the data we had we attempted to match metered fuel types and total energy consumption We were not provided with full sub-metered consumption data for the job, rather totals by fuel type. With the refurbishment already underway our client was stretched to supply further information regarding the old systems initially installed, so there was much collaboration required to try to match meter readings. Eventually we mutually agreed to move on with the next stage of the work, given our total consumption figures were within 2% of monitored data.

State of the art building simulation software... Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... With the base model complete, the next step was to include the changes put forward by our client Areas of investigation Lighting Replacing heating & cooling plant Installation of local VRF Changes to occupancy levels Improved fan efficiencies Addition of new staff & customer cafes Addition of a new bakery & hot food sales area Extra refrigerated aisles There were many changes to be included as a result of the refurbishment, and if required we could have looked at each item separately to see its direct effect, in this case the client wanted all changes included at once.

State of the art building simulation software... Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... Summary of changes CAV heating & cooling with local VRF Heating efficiency from 65% to 80% Chiller COP from 2.5 to 2.8 60% improvement in Fan SFPs Sales lighting from 40W/m2 to 30W/m2 Back of house lighting from 36W/m2 to 8W/m2 Ventilation rates unchanged It was agreed that it would be best to target the most CO2 producing elements during the refurbishment, so electrical consumption from fans & lighting were slashed, both items having a double impact in reducing heat gains to the space. The boiler and chiller were upgraded although both could have been improved further. The same CAV system was employed almost throughout using the same total volume flow rate, however local VRF units were also introduced to problem areas, meaning air could be diverted away from those areas to other parts of the store as necessary.

State of the art building simulation software... Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... With the changes made we could analyse for consumption When comparing results it is clear to see the areas of change We can view results for the whole building energy consumption or CO2 results This chart shows total energy consumption for the existing model, broken down to heating, cooling, fans & pumps, lighting, small power (i.e. heat gains to the space) and in this case ASP (power not contributing to heat gains) & catering power. If required any of these could be subdivided by fuel type.

State of the art building simulation software... Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... Just looking at the consumption & CO2 for environmental treatment elements, we can see that total energy consumption has dropped by 46% and CO2 has dropped by 50% In terms of environmental treatment, i.e. just end-uses controlling the environment within the building, savings can really be seen Both energy consumption and CO2 emissions have almost halved Whilst heating efficiency has been improved, heat gains to the space have been slashed so the heating demands are higher but being met more effectively

State of the art building simulation software... Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... Summary of improvements Energy consumption reduced by 21% CO2 emissions reduced by 22% All this despite the inclusion of: A new Café A new Staff Kitchen A new Bakery Local VRF units Increased footfall

Environmental treatment total consumption reduced by 46% Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... Summary of improvements Environmental treatment total consumption reduced by 46% Environmental treatment total CO2 reduced by 50%

State of the art building simulation software... Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... Benefits to end-client: Expected energy consumption broken down by fuel type & end use Indication of expected cuts in running costs Marketing potential

Environmental Design Solutions Ltd Copyright © 2010 EDSL www.edsl.net State of the art building simulation software... Environmental Design Solutions Ltd