Timber Buildings and Indoor Air Quality: Evaluating the Relationship Between Measured Environmental Conditions and Occupant Perception

Yilei Qiu and Samuel Stamp

The use of timber in modern construction is increasing due to its low embodied carbon and contribution to net zero goals. However, concerns remain regarding its impact on indoor air quality (IAQ), particularly through volatile organic compound (VOC) emissions, while the relationship between measured IAQ and perceived air quality (PAQ) remains underexplored. This study compares measured IAQ and PAQ in the WIP Pavilion at Robotics Living Lab, MMU, a timber-frame building, and the Student Centre at UCL, a concrete-frame building with timber interior finishes. Temperature, relative humidity, CO2, TVOC and Formaldehyde were monitored and analysed against occupant questionnaire responses. Both buildings maintained IAQ within recommended guidelines, where ventilation strongly influenced pollutant concentrations. The WIP Pavilion received the most consistent positive comfort ratings. Overall, timber did not compromise IAQ under typical operating conditions, but enhanced occupant experience through sensory and psychological effects.

Keywords: Timber Building Design, Indoor Air Quality (IAQ), Perceived Air Quality (PAQ), Environmental Monitoring.

A Sensitivity Analysis of Insulation Material and Thickness in a Timber Frame External Wall

Ghadah Altammam

Low-carbon design policy, including the Welsh Housing Quality Standard 2023, increasingly pushes designers toward higher-performance insulation to reduce operational carbon. This study asks whether this assumption holds once the whole life embodied carbon cost of that insulation is considered. A sensitivity analysis compared mineral wool (Rockwool) and PIR (Celotex) across four thicknesses (100–220mm), with U-values from BR 443, operational carbon from SAP, and embodied carbon from ICE V3 factors. Embodied carbon ranged 7.3– 7.7 tCO₂e for mineral wool versus 8.4–10.1 tCO₂e for PIR, yet even at maximum thickness, PIR cut operational emissions by only 34 kgCO₂/year. The resulting carbon payback period is approximately 71 years, exceeding the 60-year reference period. This confirms material choice outweighs thickness: minimum-thickness PIR generates more embodied carbon than maximum-thickness mineral wool. Mineral wool insulation, across the thicknesses assessed, is therefore recommended as the more robust whole-life carbon strategy within the scope of this study.

Keywords: Whole-life carbon- Embodied carbon- Operational carbon- Insulation- Timber frame

Beyond Occupant Density: The Influence of Local Bodily Proximity on Perceived Thermal Comfort During Congregational Prayer

Merve Kanidagli and Samuel Stamp

Thermal comfort assessments represent crowding through overall occupant density, potentially overlooking bodily arrangements. This study investigates whether local bodily proximity influences perceived thermal comfort during Islamic congregational prayer. A field study was conducted in the female prayer space of the UCL Student Centre. Environmental measurements were combined with post-prayer questionnaires assessing thermal sensation, discomfort, preference and tolerability. Proximity was characterised by local row and spacing conditions. Two analyses were conducted: an exploratory assessment of the full dataset and an integrated analysis filtered to comparable air temperature and relative humidity. Across both stages, closer proximity was generally associated with warmer thermal sensation, while isolated conditions corresponded to cooler sensation. The strongest effects were observed for lateral closeness such as the number of people in the same row and side spacing; whilst intermediate proximity conditions appeared the most favourable. This suggests that local bodily arrangement influences thermal experience beyond occupant density alone.

Keywords: Local bodily proximity, thermal comfort, congregational prayer, occupant density, prayer spaces