ribbon
CO2 and Other Pollutants

Emissions from Cement and GGBS Production

CO2 is acknowledged as a major contributor to climate change. In Ireland, ordinary Portland cement manufacture is the second largest industrial source of CO2 and NOX emissions, after the generation of electricity from fossil fuels. In addition, about one fifth of all dioxin emissions from industry in Ireland arise from cement production. However the production of GGBS from blastfurnace slag, an industrial by-product, generates very low CO2 emissions, and zero emissions of other pollutants. The table below shows figures for CEM I cement and Ecocem GGBS per tonne of production:

Type of EmissionsPortland CementEcocem GGBS
CO2 930 kg 0*
NOX 3.5 kg < 0.071 kg**
SO2 2.0 kg < 0.00013 kg**
CO 2.0 kg < 0.00690 kg**
PM100.4 kg < 0.0105 kg

*Ecocem’s GGBS has a carbon footprint of zero. Carbon credits from EmissionZero are used to offset the very small (less than 30kg/tonne) CO2 emissions from the electricity, gas and diesel used in the grinding process. This certificate shows the carbon footprint of Ecocem GGBS prior to the use of carbon credits to offset the remaining CO2 emissions.

**Emissions from gas used to dry material prior to grinding. Almost 80% of electricity used in the process is green, thereby contributing very little to emissions.

In Ireland, cement manufacture is the second largest industrial source of CO2 and NOX emissions, after the generation of electricity from fossil fuels. In addition, about one-fifth of all dioxin emissions from industry in Ireland arise from cement production. However the production of GGBS from blastfurnace slag, an industrial by-product, generates very low CO2 emissions, and zero emissions of other pollutants.


This chart shows that Portland Cement produces 930 kg of CO2 per tonne of output, while Ecocem GGBS produces 0 kg of CO2.

Typical CO2 emissions for Portland cement and Ecocem GGBS are illustrated graphically above.

SO2 and NOX lead to acidification of soils and surface waters and can cause nitrogen saturation in terrestrial ecosystems. Increased ground-level ozone formation is caused by NOX and CO. All of these pollutants can have direct effects on human health.

Embodied CO2

Embodied CO2 is the quantity of CO2 emitted in the manufacture, supply and construction of a building or structure.

In Ireland, embodied CO2 accounts for between 10–15% of our national emissions, which means that it accounts for between approximately 7,000,000 and 10,000,000 tonnes of CO2. This significant figure is equivalent to the CO2 emissions of 2,500,000 cars or C1 rated houses.

There are a number of reasons why more attention should be paid to embodied CO2:

  • Embodied CO2 savings can be made on a cost neutral basis by specifying/using Ecocem on your construction projects.
  • Embodied CO2 savings are more significant than operational CO2 savings because all the savings are made at the start of a structures life—it will be many years (up to 30 years) to make equivalent operational savings. The UN has stated that it is over the next 10 years we need to make significant savings or it may be too late.
  • Whereas buildings can be retrofitted to improve the operational CO2 savings, embodied CO2 savings can only be made during construction—therefore it is very important to maximise the savings day one. Using Ecocem means you are using low CO2 cement.

A lot of focus to date has been to reduce the operational CO2 of buildings or structures. This is being managed by increasing insulation, air-tightness, installing solar panels and/or biomass burners etc, and installing better glazing among other items. All of this can come at a significant cost which might get you from a C1 to an A2 rating and a corresponding saving of 3 tonnes of CO2 per annum.

Those who wish to design sustainable developments must consider both the embodied CO2 and the operational CO2. Failure to do this will result in millions of tonnes of lost savings and further damage to our ever increasingly fragile planet.

Once a structure is built, the opportunity is lost to make embodied CO2 savings: so whether you are the developer, architect, engineer, planner, contractor or other member of the project team, don’t wait for someone else to act. We all have a responsibility to leave the planet a better place then when we arrived.

Click here to find out how significant embodied CO2 is in the Irish housing industry. 59 KB PDF file

Environmental Impact of Concrete

About 90% of the environmental impact of concrete provided at the construction site derives from cement. Using GGBS as a partial replacement for Portland cement yields significant improvements in the environmental performance of concrete. The reductions achieved in various pollutant effects by using 50% GGBS per tonne of concrete are illustrated in the table opposite:

IndicatorReduction achieved
using 50% GGBS
Global Heating Gas Emission40%
Acidification34%
Winter Smog34%
Eutrophication32%
Primary Energy Requirements29%

Ireland’s obligation under the Kyoto Protocol

Ireland is committed to reductions in emissions by 2010–2012 as follows:

  • EU Directive 88/609/EEC obliges Ireland by 2010 to make reductions in emissions of SO2 by 50% and of NOX by 75%.
  • The Kyoto Treaty imposes on Ireland a substantial reduction of CO2 emissions by 2012 (limited to 13% above 1990 levels). In 2000 Ireland was 24% above the 1990 emission level. We are expected to be over 37% above the 1990 level by 2012 in the absence of corrective measures.

If Ireland fails to meet these targets, costly financial penalties will be incurred. However the use of GGBS will make an important contribution to achieving Ireland’s European and international obligations to reduce pollution. And it will do so without imposing any additional cost once the Irish Government recognises this reality.