The Building Conservation Directory 2022

PROFESS IONAL SERVI CES 1 43 C AT H E D R A L C O MM U N I C AT I O N S T H E B U I L D I N G C O N S E R VAT I O N D I R E C T O R Y 2 0 2 2 MATERIALS ANALYSTS ◾ HERITAGE TESTING LTD Unit 43, The Old Brickworks, Plumpton Green, East Sussex BN7 3DF Tel 01273 891785 Fax 01273 256545 Mobile 07714 006916 Email SPECIALISED CONSULTANCY AND LABORATORY TESTING SERVICE : In support of construction, conservation, restoration and remediation. Lead and toxic metals in paint surveys. Lime mortar, render and plaster analysis. Wattle and daub, cob, earth. Roman cement/early Portland cement. Corrosion of reinforcement and sulphate attack in concrete. Building pathology and damp. Identification of expanded insulation/cladding panel foam type. Projects include Windsor Castle, Lambeth Palace, Stephenson Bridge, Gunnersbury Park, Flaxley Abbey, Twyford Abbey, The Royal Pavilion, Clarence House, Bellenden Old School, HMS Victory, Dover Castle, Saltdean Lido, and Osborne House. See also: profile entry in Paint Toxicology, page 126. ◾ HIRST CONSERVATION LTD Head office – Laughton, Sleaford, Lincolnshire NG34 0HE Tel 01529 497449 ▪ London office – 75 Cowcross Street, London EC1M 6EL Tel 0800 917 8664 Email ANALYSIS OF PLASTER AND PAINT LAYERS : See also: display entry on the inside front cover and profile entry in Mortars & Renders, page 135. Expert assessment of historic mortars & plasters Microscopic, chemical & instrumental evaluation Full interpretation of results Mortar matching Mortar Analysis & Consultancy risk, at least in comparison to doing the physical work to the building. This means that scenarios can be explored, informing design decisions. It is crucial, however, that decisions are not driven by a crude target set against an over-simplistic model. Unfortunately, the use of Energy Performance Certificate (EPC) scores as targets falls squarely into this trap. The correlation between EPC scores and measured energy use is weak, casting doubt on the efficacy of this approach. Furthermore, a simple energy model cannot take into account the moisture risks associated with altering the thermal performance of a building any more than it can assess its heritage value. Other targets for the energy or carbon performance of retrofit projects have been proposed, for example the recent LETI retrofit guide, the AECB CarbonLite retrofit standard and EnerPHit (the Passivhaus retrofit standard). The recently launched revisions to Part L do not specify an overall energy or carbon target, keeping instead the simplified approach of elemental U-value requirements. PAS 2030, the technical standard underpinning the ill-fated Green Deal, does. Technical monitoring As the old saying goes, you can’t manage what you can’t measure. Happily, the technical and economic barriers to the monitoring of simple parameters such as temperature and humidity have fallen significantly over the decades. A temperature logger capable of running autonomously for six months or more can be had for mere tens of pounds. Much more comprehensive and sophisticated systems are also available, and as with simulation, the most appropriate tool must be chosen for each situation. An excellent approach to designing a monitoring campaign is to carefully frame a question or set of questions that need to be answered, such as ‘what temperature does the heating system deliver in the bedroom’, or ‘what is the space heating energy demand?’ With some clear questions in hand, the appropriate parameters can be selected, the accuracy and precision of sensors confirmed, and the duration of the monitoring chosen. The last factor can range from a single ‘spot’ measurement with a hand-held moisture meter for example, to a few hours during a single visit, up to days, months or years. A problem with these approaches is that they can be relatively expensive, at least in the context of single dwellings, and each building must be analysed individually; the varying patterns of occupancy, thermostat settings and so on make comparisons between buildings difficult. Recently, a number of companies have launched proprietary systems that integrate hardware and software to deliver what might be considered a ‘true’ as- built score for the building fabric alone. A range of sensors measures the energy consumption as well as temperatures, occupancy patterns and so on. Machine learning techniques are used to factor-out confounding variables to provide a result that describes the thermal quality of the fabric, irrespective of the factors that in the past made comparison difficult. CONCLUSIONS Heritage buildings have a crucial role to play in our response to the climate crisis. The carbon footprint of all buildings must be reduced, whether that be by switching to low carbon forms of energy for heating, reducing the energy demand by improving the thermal performance of the building fabric, or both. The most appropriate balance of measures will vary from building to building, and to make good decisions about this we must have a proper understanding of the thermal behaviour of each building. There are various tools available to do this, from simple observations, a multitude of measurements that can be taken and a range of calculations, models and simulations that can help us make decisions. However, these methods and tools are just part of a process which must encompass many more factors if we are to safeguard our built heritage while responding to the climate emergency. TOBY CAMBRAY is a building physicist and services engineer. He co-founded Greengauge Building Energy Consultants ( ) where he now focuses on moisture risk analysis (see page 45).