Principles of WFG system
Glass has low insulation and lets radiation through the facade, which leads to overheating (summer) or rapid heat loss winter), increasing energy demand and compromising thermal comfort.
WFG in summer
During summer WFG uses its water layer to absorb heat before reaching indoors, which protects indoors. The same heat can be reused by the mechanical system, leading to additional savings.
WFG in winter
During winter the water layer is heated, which improves thermal comfort and reduce energy consumption by having higher efficiency than a conventional heating system in the building.
Depending on the type of WFG system installed, the heat source in winter can be supplied in different ways. It can be reuse of stored heat, ground heat (pipes under the building) or a heat pump. Each case provides energy savings compared to standard.
WFG mechanical system options
Options for mechanical systems used with WFG.
This is a basic installation when WFG is installed without connections to the mechanical system. This case the energy savings are generated by the thermal mass of the infill encapsulated in the glass panel.
This case the WFG panels are connected to a thermal storage. The storage stores the absorbed heat that can be reused. This solution is ideal if WFG has ideal orientation (e.g. south wall or skylight) to capture heat.
This case we use underground pipes to heat or cool WFG (the temperature of the glass will be the same as the ground throughout the year). This is ideal for new buildings when the pipes can placed before foundation is built.
This solution has utilizes a heat pump to keep the water in the glass at a comfortable temperature. This solution is ideal for building retrofits where there is limited opportunity for storage or piping in the ground. The system can use existing heat pump, therefore it is also beneficial for projects that have heat pumps installed.
This is a special case of WFG use when there are spaces in the building with very different heating/cooling demand. WFG panels of these spaces can be connected with a water loop and move heat from one space to another. This can be beneficial when a space with cooling demand can be connected to another where heat is required.
Combining mechanical options
The mechanical options for WFG can be combined to maximize impact.
This always depends on the characteristics of the site (access to ground, space for storage) and on the function of the building (need for hot water).
For example, WFG-S can be easily combined with Advanced and Premium options (WFG-SAP).