AECB Convention 2018
This years convention took place in Garway Passivhuas Community Centre, Herefordshire.
The proceedings will be available to members here, but in the meantime, here are Paul’s highlights:
Garway Community Centre
A really well designed Passivhaus building by Simmonds Mills Architects. Lots of good details using robust but simple methods, including timber frame, interesting eaves overhangs, interesting approach to deal with level thresholds with no thermal bridges, large MVHR system that can deal with anything from 2 occupants to 100 hot bodies in the hall, with huge silencers to keep noise down.
The AECB with Tim Martel have developed an add-on to PHPP called PHRibbon, essentially an Excel toolbar that makes input of complex data such as windows, thermal bridges and variants much easier. It also features a costing section, which allows refurbishment projects to be estimated, taking areas from the PHPP multiplied by user data on costs.
Barbara Jones, after appearing on Dragon’s Den, showed her recent straw bale projects using a prefabricated system she helped develop which makes the method much cheaper and quicker.
Barbara showed her preferred foundation system which involves no concrete at all, only car tyres and pea shingle, tested to 1000kN/m².
CDM (not health and safety, but condensation, damp and mould)
A review by Dr Peter Rickaby of the Thamesmead housing estate (made famous by A Clockwork Orange) and his work in tackling terrible condensation and mould problems. He revealed that not all extract ventilation systems are equal, especially when it comes to noise levels. He described his success with Switchee energy monitoring and Aereco ventilation systems.
Bats and Breather Membranes
It has been recognised for some time that bats get entangled in modern breather membranes made from spun polypropylene fibres. Stacey Waring has been researching this for some years and found that all currently available membranes made from PP cause a danger to bats.
For some conservation projects where bats are known to be present, we have been using traditional 1F bitumen felts, we are now considering using them in lieu of breather membranes until a safe alternative is found.
More detail to follow in a future news item.
Toxic by-products of building fires
Anna Stec, Professor in Fire Chemistry and Toxicity at the University of Central Lancashire presented her research on the poisonous and irritant gases from building products given off during house fires. Many insulation products are polymers derived from oil and burn much more readily than natural materials. Treatment with brominated or chlorinated fire retardants slows down the speed of combustion, but increases the toxicity of the material, can be carcinogenic, and do not last permanently. Alternative fire retardants are being developed using materials currently used as insecticides, but these are also neurotoxic.
The builders’ favourite insulation polyurethane has a high nitrogen content, when burnt it gives off hydrogen cyanide (HCN) gas. Polyisocyanurate is a special type of polyurethane which has a higher nitrogen content, therefore gives off higher levels of HCN. HCN only lasts 24 hours in the blood stream so it is frequently not found during blood tests or autopsies.
Polystyrene does not contain any nitrogen, however, it creates vast amounts of soot, CO and CO2 which are dangerous. PVC products when burnt create soot, along with hydrogen chloride which can burn fire fighters. A particular problem is plastic fascias and soffits which drip molten material.
The materials used in furnishing our homes are equally as dangerous as those used to construct them.
The value of energy efficiency
Dr Steven Fawkes described how we should consider the wider benefits of sustainable buildings when appraising building projects, what he describes as Non Energy Benefits, eg, increased comfort; health benefits from good air quality; increased asset value due to quality and low running costs. Investors are now taking these into account, partly due to banking regulations forcing them to consider climate risks.