The owner, mechanical engineer and building operator should determine the best option for corrective action in the project. Options for corrective action include opening windows, adjusting air-handling units, alerting tenants, and increasing ventilation flow rates.
The project team and contractor work together to determine the feasibility and rough cost increase of including CO2 sensors or outdoor airflow measurement devices.
Bioinfiltration strategies on streets and parking lots such as bioswales and grass filter strips are alternatives to typical curb and gutter design that allow for infiltration of stormwater, as opposed to conveying the runoff to storm drains.
Mitigate cost premiums by getting the most from stormwater strategies. Onsite treatment and retention strategies like green roofs and rainwater cisterns can be costly, but may serve additional purposes and contribute to other LEED credits, including open space requirements (SSc5.2), mitigating the urban heat island effect (SSc7.2), and reducing potable water use for landscaping (WEc1). Features such as constructed wetlands, green roofs, and bioswales can also increase property value.
Green roofs can reduce peak runoff rates on developed sites. However, the volume reduction potential of any green roof will depend on its moisture-retention capacity, which depends on the soil profile. One storm may saturate the soil, leading to a conventional amount of runoff resulting from a second storm in close succession.
Porous pavement can be incorporated into many sites and climatic conditions. Proper design, installation, and maintenance is important. Work with an experienced contractor, and verify that porous paving will work with your site’s climate and soil conditions. For example, snowplowing, sanding, and salting can damage porous paving.
In urban areas and sites with little land, use a variety of features to achieve project goals. For example, green roofs and rainwater cisterns may be effective in these situations. Capturing rainwater for irrigation reduces the amount of stormwater runoff leaving the site as well as outdoor potable water use. Reusing captured rainwater for toilet flushing has similar effects, in addition to reducing potable water use indoors.
Detention ponds with controlled release structures only help to reduce the rate of runoff, not the volume. If a detention pond is going to be used onsite, other means of facilitating infiltration must also be used to meet the credit requirements.
