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Sustainability auditing and building upgrades: making sure you get the whole picture

Written by  Stephen Choi and Dr Rory Eames / 01 September 2014
Published in Retrofit News DISQUS_COMMENTS
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Sustainability auditing is a term used when the depth and breadth of a traditional energy audit (for example AS/NZS 3598:20001) is considerably expanded. Many building owners and facilities managers will have experienced a lack of enthusiasm in the face of energy audit recommendations. As the low-hanging fruit of energy efficiency rightly dwindles, and buildings, owners, and occupiers demand more (and know more) about the assets they own, operate and spend considerable time in, the need to have insightful assessments about retrofit and refurbishment options must significantly improve.

The solution lies in the quality of the assessment, and the quality of the questions being asked on behalf of the asset manager, or owner. In other words, from undertaking and reviewing many energy audits over the years, we believe that asking deeper and better questions is yielding far more productive results for building owners than the traditional energy audit alone. It is also important to understand that sustainability auditing is not a proxy for energy auditing. Sustainability auditing explicitly brings into question the accuracy of all data and its analyses upon which retrofit or refurbishment recommendations are based.

At present, there are three levels of energy audits (Levels 1, 2 and 3), and these vary significantly in accuracy (from +/- 40 per cent in Level 1 to +/- 10 per cent in Level 3), and, accordingly, in how much they cost a client to commission (ranging anywhere from $10,000 to $100,000). While it is common to find that all three different levels of audit types to the same building can be similar, in that they may well produce the same final ‘kilowatthour or megajoule figure’ for annual consumption, they can differ greatly in terms of how much energy was being used, by what, and when – the really useful stuff for project managers and building owners. Very rarely do we see anyone ask why energy was being consumed ‘by the building’. This is where we believe the accurate auditing of energy requires looking beyond energy.

A good example from a project can be used to show what we mean here, and there are many others besides this one. A multi-residential apartment building had previously had two energy audits undertaken, with the main recommendation being to replace the building’s gas domestic hot water system with a gas microturbine. This was because the building’s annual energy use for hot water was almost 300 megawatt-hours (just over one million megajoules) – equivalent to 40 per cent of the total annual energy consumption of the building. We asked why this much hot water was being used in this building.

Surprisingly, in neither audit was the question addressed. Both audits had simply understood there to be a large requirement for hot water, and proposed a technological solution to delivering that large requirement in a ‘more efficient’ way.

Our conversations with 22 residents from 15 different units revealed the same responses several times in this building – thermal comfort was by far the biggest complaint by the occupants. We returned to the previous audit to look at the heating system (which was electric) to find that there were no problems identified in the report. In fact, it suggested that heating accounted for just 2.3 per cent of the total annual energy consumption – and therefore any upgrades to deal with space heating demand would provide no payback.

Further investigation was warranted, so with the collaborative effort of the very engaged building owner, we measured (not assumed) what people were using electricity and gas for, how much they were using, and why. The following is what we found:

  1. The heating system actually accounted for eight per cent of the total annual energy consumption, and not 2.3 per cent as had been estimated.
  2. Sixty per cent of residents had brought their own plug-in heaters to replace the inadequate existing heating system, taking the real heating load account to 12 per cent of the total annual energy consumption – yet people were still thermally uncomfortable.
  3. General plug loads accounted for 30 per cent of all electricity consumed – with south-facing apartments consuming up to double that of the apartments facing north.
  4. Half of all the mains water consumption in the building was being heated by the gas hot water system. The configuration of the hot water system accounts for some unnecessary gas consumption, as we found that around one-quarter of gas used in the system was reheating a portion of previously heated hot water that was being recirculated, but not used.
  5. Internal air temperatures in rooms without self-bought plug-in heaters tended to closely track external conditions; meaning that the building fabric was doing little to buffer external conditions.
  6. We discovered excessive condensation and mould in southfacing ground floor bedrooms. This was a result of: a. low internal air temperatures (due to a thermally poor building fabric and inadequate heating) b. poor natural ventilation (due to the perceived security risk of opening ground-floor windows) c. high relative humidity levels (due to low air temperatures, inadequate ventilation and a lack of clothes-drying space).
  7. The air permeability of the apartments was approximately 24 air changes per hour at 50 Pascals of pressure, explaining, in part, why the apartments feel draughty and track external conditions. The test also uncovered a non-BCAcompliant smoke shaft.
  8. In overcast conditions, natural light levels at occupants’ working planes (for example, study desks) reached 500 lux in the northfacing apartments and only 80 lux in south-facing apartments .
  9. Across 30 occupants over the month of October, the average shower time was 16 minutes, with the longest recorded time being 41 minutes. People were doing several quite unexpected, yet understandable in context, things to keep warm; taking long, hot showers was one of them.

None of the data mentioned here were uncovered in any of the previous audits, and naturally there were no recommendations to improve any of the issues. Rather than providing a list of technical recommendations to make one problem ‘less bad’, the key to this project was not technological, but rested on the quality of the investigation, and the right combination of technical building knowledge, lateral thinking, and enthusiastic investigation. This resulted in a more accurate suite of retrofit works, such as insulating the walls, installing draught-stripping and removing the ill-placed solar shading on the south side of the building, and then assessing the inadequate heating.

Read 2082 times Last modified on Tuesday, 02 September 2014 13:26
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