Structures such as buildings, the surrounding terrain, landscape features, street corridors, and open areas such as fields, parks, parking lots, and bodies of water all significantly affect microclimatic wind patterns. Very often these features create or exacerbate wind problems at the pedestrian level. Every object has an effect on the wind. To ensure the comfort and safety of people, Theakston Environmental is employed by architects, planners, and engineers to consider building design, location of buildings, road placement, parks, and open spaces.
Using Site and aerial photographs, survey footprint maps, and computerized digital data when available, Theakston technicians build an accurate physical scale model. The model is tested in a water flume where the movement of water simulates wind currents. Special wind velocity probes determine wind speeds at key locations and wind velocity under various wind speed and direction scenarios. A specially designed computer program processes the data collected. The analysis shows comfort levels of the key locations, pinpointing problems before construction. Areas identified as unsafe or uncomfortable through physical model analysis are mitigated and subsequently retested at the facility to ensure the desired comfort criteria is achieved.
Blowing and accumulating snow is a potential hazard for people and structures. Highway accidents often result from “white-out” conditions and black ice, caused by combined action of wind and snow. Near Barrie, Ontario, 12 people died in a massive automobile accident on Highway 400, due to “white-outs”. Theakston participated in the inquest and found that simple wind altering devices could have prevented the “white-out” condition which lead to the accident.
Snowstorms are simulated by using silica sand to represent snow and flowing water to represent wind. The ground snow load is determined using the National Building Code and is duplicated in the laboratory facility. The result of introducing the sand into the model is a photographic illustration, including depth measurements, of what the snow patterns would be. Areas that are scrubbed clean by whirling vortex winds can be seen as well as points of high accumulation. Mitigative devices are often simple adjustments or additions to the site plan to alter the wind patterns. Such alterations improve the comfort of the area and protect the structural integrity of the building.
Pollutants discharged from power plants, commercial buildings, industrial processes, or hospitals can be carried for some distance with fallout occurring on neighbouring properties. Stack emissions are often ingested into a neighbouring building’s ventilation system and subsequently distributed throughout the building. Corrective measures can be taken for these and other conditions contributing to 'sick building syndrome'.
Due to the complexity of variables involved, computational plume dispersion models are typically designed to yield conservative concentration results. Numerical models are used as a preliminary assessment tool to ascertain potential problem areas. Exhaust gas dispersion is simulated by introducing dyed water as the stack emission into a model placed in the water flume. This procedure provides immediate visual results since it permits observation of potential problem areas. We employ specialized photographic equipment and techniques to capture and document plume trajectory. The technique used for physical modeling is unique to Theakston Environmental and allows complete mapping of 3-D plume trajectories and determination of concentrations at critical points of impingement.
Tall buildings, irregularly shaped buildings, or buildings in close proximity create unique wind flow patterns. These may result in excessively high pressures that are difficult to anticipate based on experience alone. A better understanding of the wind’s interactions with buildings more than negates these concerns; it allows innovative building forms, along with optimized structural systems. A wind pressure analysis will determine the magnitude of the pressures required for design, to prevent dangerous failures and keep costs in line. These analyses can be applied to the entire structure or specific design features.
Wind pressure analysis requires construction of a detailed scale model of the proposed building and other significant structures in the vicinity. Pressure taps situated on the surface of the proposed structure(s) permit measurement of detailed surface pressure distribution. Wind pressure data provides peak, mean, minimum, and rms coefficients of exterior pressure at each tap location for 36 wind directions. These are combined with the statistical wind climate for the area to provide predictions of peak exterior pressures and suctions for various return periods. The results are used to design wall and window systems, roof surfaces, ventilation intakes, exhausts, and accesses, eliminating what have proven to be potential problem areas on numerous occasions.
Particulate can be described as minute separate particles of any kind that have the tendency to move by wind forces. It is carried by wind to areas beyond a project site and, as a rule, upsets the local environment. Particulate dispersion can be brought into compliance with regulatory bodies by proper control of emissions through mitigation. We have conducted studies for asphalt plants, open pit mining operations, landfill sites and compost sites. The highly visible nature of the water flume has allowed Theakston to create tests for wind-borne particulate.
Dye or silica sand is used to provide a highly visible indication of the route that dust or odour will travel. Photographic records of the dye and sand dispersal patterns are analysed along with wind velocity measurements to determine the route the emissions travel and their downwind effects. Theakston Consultants will suggest how the surrounding area could be altered to reduce the impact of particulate emissions. Mitigative devices are designed, installed, and tested before being recommended for site installation.