HISTORIC STRUCTURE MONITORING
The Research Behind Renovation
Building science may have advanced a lot in the last 100 years, however many of our historic buildings are not only still standing, but in active use. When it comes to renovating these structures, construction teams will face many challenges - not least of which is understanding what is currently happening within the assembly. SMT has years of experience installing sensors to gather invaluable data, allowing renovation teams to move ahead with confidence that their methods will not damage the valuable historical features of the structure.
Case Study: Seattle Asian Art Museum
A long-term monitoring program was implemented at the Seattle Asian Art Museum to characterize exterior wall assembly performance and interior operating conditions prior to complete Renovation.
The purpose of the monitoring system was to analyze the effect interior operating conditions have on historic building enclosure components, which include sandstone veneer walls, exposed concrete walls, skylights, and art deco aluminum frame glazing systems.
Building a Network
The building was monitored using a combination of specifically positioned temperature, relative humidity (RH), surrogate moisture content, pressure, and condensation sensors.
The sensors are wired to data-loggers placed nearby, which are in turn wired to a central computer for upload to an internet based server and software review system.
The monitored data collected from the sensors is used to assess the performance of the building enclosure components, and assist with the renovation design.
SMT has been an IoT (internet of things) based company since its inception. The beauty of having a cloud-enabled sensor network installed is that it allows remote monitoring of difficult to reach locations.
Picutred opposite is a sensor embedded into the external sandstone wall, several stories up. It would have been completely impractical to manually take readings from this location, however remote access allowed the client to capture valuable data over a prolonged period without ever having to get a ladder!
Building a Model
Sensors were installed in specific points around the site, measuring multiple different factors at play within the building envelope.
The measured data was used to calibrate hygrothermal models, and a parametric analysis performed to determine the potential effects adding insulation may have to existing wall performance in order to develop appropriate design solutions for the renovation.
Pictured: An SMT technician installing sensors to understand how a skylight was impacting internal conditions.
The first year of data revealed several interesting facts about building enclosure performance and building operation:
Past renovations negatively affect the hygrothermal performance of sandstone clad wall assemblies
Condensation occurs frequently on glazing assemblies
Interior wall surface temperatures are conducive to condensation formation behind displays
The mechanical system creates large pressure differentials under normal operation
Tight control of temperature and RH is a constant challenge.
Data for the complex internal dynamics of the SAAM yielded invaluable insight and helped protect priceless works of art.
Case Study: Ottowa Heritage Building
The environment can pose a threat to the health of buildings, structures, and contents; therefore, any conservation or preservation project needs to take into account the original envelop of the building, its original context, and its new or proposed purpose.
SMT was contracted to provide sensors and training for a hygrothermal monitoring project of an Ottawa area heritage mass masonry wall system.
Historical wall assemblies are often idiosyncratic in their construction, and before installing hardware in the existing valuable structure, a mock-up is created.
These mock-ups simulate the conditions our install teams can expect at the real site, allowing them to perfect their intsallation techniques and properly callibrate their equipment.
These mock-ups also create opportunities for training.
A Suite of Sensors
This project required a variety of sensors, including:
A3-8R USB data loggers
A3-4V/4R USB data loggers
MF52 30ft lead temperature sensors
HTM2500 30ft lead 1/8” jack RH sensors
EMS 30ft lead moisture/temp sensors
1”H2O Differential Pressure sensors
1pr 22awg stranded, shielded sensor wire
Weather Station with non-penetrating
roof mount and solar power / battery storage
Check out our products page for more info
Pictured: SMT A3 Data Logger
Masonry Under Threat
One of the largest threats from the environment is the moisture content since excess moisture content in interior and exterior of the structure and components can lead to:
Frost damage from freeze-thaw cycles, cooling rate, and water content
Salt crystallization on the surface and interior of the structure
Leaching of components of the mortar
Potential damage from moss, climbing plants, and moulds
SMT developed and callibrated dielectric moisture sensors specifically for installation in heritage buildings. Designed to be easliy installed with minmal damage to the exiting structure, the dielectric moisture sensor is linked to an A3 data logger.