Put remedial works ahead of renewables

With legislation driving the improvement of existing non-domestic building stock, various ways are currently under consideration to reduce the built environment’s use of energy and production of carbon dioxide. Renewable technology and the production of greener energy (with added incentives of financial reward via feed-in tariffs and renewable heat incentives) are proving the most popular ideas for achieving this. However, there is a far more straightforward process equally capable of delivering financial gain which is being overlooked. Stroma suggests that building fabric improvement should be the first step towards meeting targets.

Generally, buildings constructed before 2002 – when Part L introduced maximum levels of air permeability – were built with little concern for an airtight building envelope. As a result, they suffer unnecessary energy loss – this is especially true of complex, steel-framed or energy-intensive buildings. Addressing this through fabric improvement works can significantly reduce energy usage for heating, and is therefore an easy step towards meeting energy performance requirements.

The first stage is an air-tightness test to determine the current air leakage rate. If the result is high, pressurised smoke testing is undertaken to locate the main leakage areas. Next is to create a dynamic simulation model, a virtual 3D model of the building within which all aspects – including air-tightness – can be varied and the effects observed. Thus the feasibility of different improvement scenarios can be explored. DSM is intelligent software able to predict changes to space heating/cooling loads resulting from various remedial works. From this, the resulting financial and energy savings can be estimated, and the payback period gauged. Therefore property owners, managers and landlords can invest wisely, justifying expenditure against future energy cost savings.

Of course, the analysis is not infallible. While neither the second test result, nor the state of energy costs throughout the payback period can be predicted with absolute accuracy, the same element of risk applies to most alternative energy reduction strategies.

Often, remedial air-sealing works prove the most cost-effective option, promising significant improvement at a realistic predicted payback period. Once the necessary work is completed, another air-tightness test is conducted to ascertain the actual level of improvement and firm up the payback calculation.

It is a passive approach, involving minimal disruption; work can be flexible and need not affect the building’s day-to-day operations. Furthermore, the process is robust. Results can last the lifespan of the building, eradicating operation and maintenance issues.

Additionally, there is no emphasis on changing occupancy patterns or behaviour, as is the case with many renewable technologies; comfort levels are improved automatically. Structural benefits include reduced noise ingress and interstitial condensation.

Targeted introduction or improvement of insulation can be similarly facilitated by another non-invasive testing technique: thermography. Using sophisticated infrared thermal imaging cameras, experienced thermographers can identify areas of a building where surface temperatures might indicate a problem with insulation. The associated remedial works can be more involved than air-sealing, but are often perfectly justifiable based on the same DSM-based predictions.

Improving building fabric in these ways can form part of a coherent CRC compliance strategy as meter readings will reflect the improved energy performance. In addition, they can help improve the EPC rating, as currently EPCs for buildings constructed prior to 2002 in England and Wales must assume a high air permeability rate of 25m3/(hr.m2) @ 50Pa.

Detailed findings into the benefits of improved building air-tightness are due for release shortly. However, Stroma has completed its own research using residential ‘co-heat’ testing, which calculates a building’s thermographic properties by relating the thermal equilibrium state back to the power required to maintain the pre-set internal temperature. In one case study, Stroma discovered that improving air-tightness from a poor rating – 20m3/(hr.m2) @ 50Pa – to the Building Regulations standard of 10m3/(hr.m2) @ 50Pa, delivered a 25 percent reduction in energy usage for space heating. Improving building fabric is therefore a cost-effective and long-term solution to environmental challenges.

To find out more about Stroma, Tel: 0845 621 11 11, email: comply@stroma.com, or visit: stroma.com