Why you should use a catalytic convertor alongside Combined Heat and Power (CHP) to significantly reduce your NOx emissions.
Are you undertaking a building project, a new development, or refurbishment fit-out?
- Insulated your building to eliminate heat losses?
- Actioned energy saving measures to reduce your energy demand?
- Replaced old inefficient equipment with high efficiency systems, to further minimise your energy consumption?
- Implemented low-carbon technologies to save more energy and reduce your CO2 emissions (and reduce your energy costs)?
By doing the above, hopefully you should have achieved compliance with the Building Regulations Part L and gained that all important energy performance certificate (EPC) with an ‘A’ rating!
But have you achieved approval for your building’s environmental impact and its future sustainability?
Air pollution has a negative impact on our health and the ecosystems we rely on, and it also degrades building materials. And, unfortunately, air pollution can travel over long distances.
The reaction of nitrogen and oxygen from air during the fuel combustion process associated with energy generation also produces toxic air pollutant nitrogen oxides (NOx). NOx gases can react to form smog and acid rain.
The current Building Regulations set controlling limits for CO2, but not for NOx. But that doesn’t mean NOx emissions will not be a future part of these regulations.
By lowering your overall energy use, you will have reduced CO2 emissions without indirectly reducing NOx.
Environmental assessment standard BREEAM (increasingly becoming part of planning approvals) for industrial and commercial buildings considers pollution as one of its main sections – including NOx emissions from space and water heating systems.
The credit allocations for a reduction in NOx emission levels, as per BREEAM POL 02, are:
|Building Types||NOx Emissions for heating and hot water (mg/kWh)||BREEAM credits|
|Non-industrial (all building types)||≤100||1|
|Non-industrial (all building types)||≤70||2|
|Non-industrial (all building types)||≤70||3|
The UK is generally meeting the EU national emission ceilings (NECD) for pollutants. NOx emissions fell by 69% between 1970 and 2014.
There was an 8% decrease in 2014 compared with 2013 – but the rate of reduction has slowed.
‘There was a steep climb in NOx emissions between 1984 and 1989. Catalytic convertors and stricter emissions regulations resulted in a strong downward trend since 1990’ – Department For Environment, Food & Rural Affairs.
The Gothenburg Protocol requires the UK to reduce NOx emissions by 55% compared with 2005 emissions.
Air quality in cities
Air quality, especially in highly populated areas, is a big concern.
Major cities are taking steps to reduce the impact of air pollution by setting tough air quality assessment benchmarks for NOx emissions. The Greater London Authority (GLA) has done this in the London Sustainable Design and Construction Planning Guidance (SPG).
This sets much lower emission ratings, which can be as low as 95 mg/Nm3, compared with the more widely set limit of 250 mg/Nm3.
So could you meet future policy changes if this limit, or an even lower limit was applied in your area?
Future-proof now using a catalyst
Catalysts help reduce levels of NOx where the specified limits are low.
Combustion exhaust gases are passed through a catalytic convertor that contains a catalyst. A chemical reaction occurs on the catalyst surface, breaking down the NOx into nitrogen and oxygen, which are safely emitted into the atmosphere.
Some small-scale Combined Heat and Power (CHP) systems are designed for Ultra-Low NOx emissions by fitting an internal catalyst that will significantly reduce your NOx emissions to 50 mg/Nm3. This is achieved without reducing the overall efficiency of the CHP system in generating both low carbon electricity and heat and without increasing the footprint of the CHP.
Ultra-Low NOx emissions have been achieved by redesigning the internal catalyst area to increase the chemical reactions.
For larger turbocharged Combined Heat and Power (CHP) systems, Selective Catalytic Reduction (SCR) reactors have to be installed within the plant room. This can bring NOx emission levels down as low as 10 mg/Nm3, if necessary. However, this is both a costly solution and has twice the footprint of the original CHP
Importantly, the catalyst needs to be fit for purpose for its lifetime operation; in this way, it will future-proof your building.
- Eliminate energy waste and minimise energy demand in your building.
- Use energy efficient low-carbon technology, such as Combined Heat and Power (CHP), and keep CO2 and NOx emissions to a minimum.
- Check local authority guidelines for lower than normal NOx emission limits.
- Use a catalyst to reduce NOx – some Combined Heat and Power (CHP) design ranges have Ultra-Low NOx options.
Discover how to plan your building or development so that it can hit energy targets, ensure regulatory compliance, and be sustainable. Download Building for the future: how decisions at the planning stage can help you create an energy efficient building fit for the 21st century.
Topics: Building Design