Energy prices are rising while initiatives like Feed in Tariffs and the Renewable Heat Incentive are enabling consumers to make a return on investment in renewable technologies. As a result, consumers are turning to renewables to generate their domestic energy and as such, there is increasing demand for these products to be installed either at the time of construction or retro-fitted to an existing home.
General requirements for the installation of these technologies are available; however there is a lack of European or British Standards specifically relating to their mechanical fixing and installation onto buildings. Competence to install these technologies through nationally approved qualifications is still in its infancy and some failures as a result of poor installation have become apparent.
In response to such issues, the NHBC Foundation has produced a Guide to installation of renewable energy systems on roofs of residential buildings.This guide provides best practice advice on wind- and weather-resistant installation of roof mounted Solar Photovoltaic (PV), solar thermal and micro-wind turbines.
SOLAR POWER: Solar PV and solar thermal systems installation
PV and solar thermal systems use panels that harness the sun’s energy – called ‘modules’ in a PV system and ‘collectors’ in a solar thermal system – which are commonly located on the roof of a dwelling. It is vital these systems do not compromise the roof’s waterproof envelope, which prevents rain from penetrating into the home – a problem encountered with installation of some PV systems.
The roof must be capable of taking the weight of both the panel plus any additional load, such as water or snow, which could build up during adverse weather. Solar thermal systems subject the added weight of heat conducting fluid and pipe work onto the roof structure and it is therefore important that a thorough assessment of the roof structure is conducted before installation takes place.
There are two main types of installation for PV and solar thermal systems:
1) Integrated into the roof structure – where the panel must provide a weather proof covering for the building as well as generate power. The interface between the panel and the adjacent roof covering should be weatherproofed. The guide explains how this can be achieved and details how installers should provide adequate ventilation on the underside of the system.
2) Mounted above the existing roof covering – where panels are designed to transfer any load, such as rain or snow, onto the roof at mounting points. If not installed effectively, water penetration can occur at fixing points and where electrical connections penetrate the roof envelope. The guide takes the reader through various options for installation to avoid water penetration, examining various types of hook fixings, solar support tiles and bolt through fixings and, in the case of solar thermal systems, good practice for underlay penetrations.
WIND POWER: Micro-wind turbines
There are two basic types of wind turbine available for domestic use, the more common horizontal axis wind turbines (HAWTs) and vertical axis wind turbines (VAWTs). Both harness the power of wind and, in the domestic setting, usually generate electricity.
Turbines can be either roof-mounted, a term which includes devices mounted at high level on external walls, or stand alone mast-mounted. Turbines could have a working life of 20 years but this will be very dependent on them being installed correctly and being suitably maintained all of which will reduce the likelihood for costly replacement.
The guide highlights the importance of an effective fixing to secure a turbine to the structure, particularly where mounted to the wall. This will reduce stress and prevent the turbine itself from coming loose. Installation should take into account the impact of wind loads on the turbine, the vibration and movement of the turbine itself on the fixing over time, and the potential for corrosion of the fixing caused by rainwater.
It is also important that routine maintenance checks are carried out and, in particular, that all fixings are regularly inspected. The guide recommends methods of strengthening the fixing of the turbine, for instance by using galvanised steel that is not easily eroded and installing resilient pads with the brackets to dampen vibrations from the turbine.
Meeting standards
The guide concludes by listing the product and installation standards for renewable technology that apply in the UK. While renewable technology holds great opportunity for home owners to reduce their reliance on the national energy grid and decrease their home’s carbon emissions, the positive effect could be undermined if the technology is not correctly installed.
Posts
0 comments:
Post a Comment