CLAIH assessment

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Climate change, air quality and housing – future challenges to public health (CLAIH)

 CLAIH analytica model



The purpose of the assessment is to evaluate cost-effectiveness of different measures to reduce green house gas emissions from household heating in Finland when costs from indirect health impacts of the measures are also taken into consideration.

More specifically:

  • What would be the health impacts of different options for heating system and energy efficiency renovations in detached houses constructed in 1960-1970?
  • From the society's point of view, what would be the most cost-effective (combinations of) measures to reduce green house gas emissions from this type of houses?
  • Is there a conflict between the cost-effectiveness of different measures when either a society or a house owner is considered?


  • Population: Finland
  • Assessment time frame: 2010-2030
  • Evaluated activity: heat consumption in detached houses
  • Evaluated exposures:
    • Fine particles (PM2.5)
    • Indoor Radon
    • Indoor dampness and mold
  • Evaluated health impacts:
    • Mortality (and morbidity?) due to long term exposure to PM2.5
    • Lung cancer mortality due to indoor radon
    • Asthma due to indoor mold and dampness
  • Other evaluated emissions: CO2
  • Evaluated costs for a house owner:
    • Cost of heating system renovation (investment, interest)
    • Cost of energy efficiency renovations (investment, interest)
    • Cost of heat consumption (heat energy, maintenance)
  • Evaluated costs for society:
    • Costs for house owner (excluding taxes)
    • Cost of health impacts
    • Cost of CO2 emissions

Specific decisions evaluated

  • New heating system
    • Light oil
    • Pellet
    • District heating
    • Direct electricity + air heat pump
    • Ground source heat pump (GSHP)
  • Form of district heat production (evaluated only in terms of PM2.5 health impacts)
    • BAU
    • Small scale power plant (<5 MW), wood
    • Small scale power plant (<5 MW), oil
  • Energy efficiency renovation
    • BAU (no renovation)
    • New windows
      • (U factor 1 W/m2K, air leak factor reduced by 20% to 0.24/h)
    • New windows + increased insulation for walls and roof
      • Wall U factor 0.17 W/m2K
      • Roof U factor 0.09 W/m2K
      • Air leak factor reduced by 50% to 0.16/h
    • New windows + increased insulation for walls and roof + heat recovery ventilation
      • Heat recovery efficiency 60%

Emissions, health impacts, and costs are evaluated for:

  • An average detached house constructed in 1960-1970
    • The house is in need of basic renovations unrelated to energy efficiency improvements
      • New heating system (excluding heat distribution system)
      • New windows
      • Wall renovation
  • All houses houses similar to the one described above in the Finnish building stock?
    • All changed at the start of the assessment follow-up period?
    • Changed gradually throughout the assessment follow-up period?

Intended users

  • Ministry of Employment and the Economy
  • Ministry of Social Affairs and Health
  • Ministry of the Environment
  • Any interested party


  • Anyone interested



The objective of the preliminary assessment has been to find out the current level of health impacts related to residential heating and indoor air exposures. The future results (year 2030) have been calculated assuming that things in housing stay pretty much the same as they are now. However, population aging is taken into account.

The preliminary results are based on the following assumptions:

Building stock:

  • Annual building stock loss is 0.3%. Only buildings older than 50 years are pulled down.
  • Annual new building stock construction is determined based on the annual building stock loss (0.3%) and annual increase in the residential surface area per person (0.7%)
  • All new buildings are current standard in energy efficiency.
  • Fraction of heating systems in new buildings is the same as in the buildings constructed between 2000-2010.
  • No heating system/energy efficiency renovations are done in the current building stock.
  • Energy efficiency of buildings constructed at different decades is based on the building restrictions at the construction time.

Energy production/consumption:

  • District heat production:
    • 75% in large CHP plants, 25% in small scale heat production plants
    • Fraction of used fuels is based on the year 2008.
    • These are assumed to stay the same in the future.
  • Electricity production (fuel fractions) is based on the year 2008. This is assumed to stay the same in the future.
  • Only primary heating systems in the residential buildings are included in the assessment.
  • Fraction of the combustion techniques used in the domestic wood heating is based on fractions used for primary wood heating in KOPRA-project.
  • Temperature increase due to climate change is not taken into account.

PM2.5 exposure:

  • Only emissions to outdoor air are included in the assessment.
  • PM2.5 emission intake fraction for domestic combustion is based on the PILTTI-project.
  • PM2.5 emission intake fraction for large and small power plants are based on KOPRA-project.
  • Exposure-response function (RR) for PM2.5 exposure and natural mortality is based on the Tuomisto et al. 2008 expert eliciation study (0.97% (90% Cl 0.02-4.54) per 1 µg/m3 increase in PM2.5.
  • Exposure-response function (AR) for PM2.5 exposure and new cases of chronic bronchitis (age group >27) is 0.0000533 (95% Cl 0.0000017-0.000113) per 1 µg/m3
  • Exposure-response function (AR) for PM2.5 exposure and restricted activity days (RADs) (age group 15-64) is 0.902 (95% Cl 0.792, 1.013) per 10 µg/m3

Mold and dampness exposure:

  • Prevalence of mold and dampness exposure in Finnish residences is 15% This is assumed to stay the same in the future.
  • Exposure-response function for mold and dampness exposure and current asthma is all age groups is 1.56 (1.30–1.86) (Odds ratios for asthma in homes with vs. without visible dampness and/or mold or mold odor)
  • Asthma prevalence in Finnish population is 8% (assumed to be the same in all age groups)

Radon exposure:

  • Average radon concentration in Finnish residences is 120 Bq/m3. This is assumed to stay the same in the future.
  • Exposure-response function (RR) for radon exposure in home and lung cancer mortality is 1.16 (95 % CI 1.05 - 1.31) per 100 Bq/m3.


  • Assessment takes into account population aging
  • Baseline risk of natural mortality and lung cancer mortality is assumed to stay on the year 2008 level.


Total heat purchase of residential buildings by heating type, kWh/a

Heating type 2010 2030
District 1.84G 1.99G
Light oil 1.53G 1.38G
Wood 1.02G 1.03G
Electricity 1.83G 1.98G
Geothermal 0.35G 0.54G
Other 0.78G 0.92G

Total PM2.5 emission from residential building heat production, t/a

PM2.5 source 2010 2030
Domestic combustion 6000 5880
Small power plants (<50 MW) 290 310
Large power plant 820 890

Average population exposure to PM2.5 due to residential heat production, µg/m3

PM2.5 source 2010 2030
Domestic combustion 0.53 0.53
Small power plants (<50 MW) 0.005 0.005
Large power plant 0.01 0.01

Annual health impact of PM2.5 exposure from residential building heating. DALY: disability adjusted loss of life years.

Health endpoint 2010 2030
Attributable deaths (all natural) 283 373
DALY: mortality 3177 3583
Attributable new chronic bronchitis cases 107 101
DALY: new chronic bronchitis cases 129 121
Attributable restricted activity days (RAD) 166100 133500
DALY: RAD 45 36

Annual health impact of exposure to indoor mold and dampness. DALY: disability adjusted loss of life years.

Health endpoint 2010 2030
Attributable cases: asthma 28090 27260
DALY: asthma 1657 1608

Annual health impact of exposure to indoor radon. DALY: disability adjusted loss of life years.

Health endpoint 2010 2030
Attributable lung cancer deaths 381 440
DALY: lung cancer mortality 5782 5936

Things to discuss in the meeting:

Mold and dampness

  • Relevance of the asthma prevalence assumption
  • Relevance of the exposure-response function for mold and dampness exposure and asthma
  • Other possible health endpoints for mold and dampness exposure
  • Relevance of the used mold and dampness exposure indicator
  • Factors related to mold and dampness exposure and health effects
  • Important things to consider when modelling changes in building stock and the effect these changes have on the mold and dampness exposure and their health effects


  • Updates for PM emission factors?
  • Updates for fractions of domestic wood burning devices?
  • Health endpoints included. Options:
    • Natural mortality (PM2.5, long-term exposure)
    • Cardiovascular mortality (PM2.5, long-term exposure)
    • Lung cancer (PM2.5, long-term exposure)
    • New chronic bronchitis cases (PM2.5, long-term exposure)
    • Restricted activity days (PM2.5, short-term exposure)
    • Work loss days (PM2.5, short-term exposure)
    • Minor restricted activity days (PM2.5, short-term exposure)
    • Lower respiratory symptoms (PM10, short-term exposure)
    • Cardiovascular hospital admissions (PM10, short-term exposure)
    • Respiratory hospital admissions (PM10, short-term exposure)
    • Medication usage by people with asthma (PM10, short-term exposure)
  • Should secondary PM2.5 be included in the assessment?
    • Possibilities for exposure modelling (intake fractions are only for primary PM2.5)
  • Should PM10 be included in the assesment?
    • Possibilities for exposure modelling
  • PM exposure assessment: outdoor air concentrations vs. personal exposure approach


  • Heat exposure impact assessment is a separate assessment.
  • Building stock development does affect heat exposure, but it would be very dificult to evaluate health impacts from this.
  • However, the effects of the building energy efficiency solutions on indoor temperatures can, perhaps, be analysed in some other qualitative or quantitative terms.

General issues

  • Assessment focus, specific questions asked, issues included
  • As of now, possible decisions on the following issues are to be assessed:
    • Heating options for new residential buildings
    • Heating system renovations in old building stock
    • Energy efficiency in new building stock
    • Energy efficiency renovations as part of general renovations in old building stock
      • Improved wall insulation
      • Heat recovery from air exchange
      • Improved window insulation
    • Air filtering in residential buildings
    • Form of district heat production (more small scale production?)
    • Fuel options for district heat production

Main objective is to answer: what would be to most cost-effective policy options for the society to reduce CO2 emissions from residential heating when the cost from indirect health impacts is taken into consideration?



Plan for uncertainty calculations

The final endpoint of the Claih model is Cost share (or total cost, which is the same with cost factors summed up). The health cost part is the heavy part of the model. Thus, if the heavy chain that ends to Total cost of lost life years can be removed and calculated outside Analytica, then all other parts can be calculated there. The idea is that Analytica calculations are converted by MDArrayToTable into a 2D table with Run as one index. This is exported to a file and then imported to R-tools as a static input.

In Analytica, a new node Cost share w/o health is needed: it calculates everything ecxept health, and is then exported to Opasnet. The final cost calculations and VOI analysis is done in Opasnet.

To calculate health impacts, the following nodes must be recoded in R and computed there:

  • YLL total
  • YLL, specified
    • Mortality, specified
      • Population in time, average for time step *
        • Population in time child *
          • Birth rate
    • Age-adjusted life expectancy
      • Population in time, beginning of time step *
    • Age weight
    • Life years in time
    • PV of a life year
  • Year help
  • Value of a life year
  • Present value
  • VOI (this is a function)

* These three nodes have the most complex code.

Also, these input nodes must be calculated in Analytica, converted, and exported to R-tools:

  • Mortality risk scenarios
  • Population data

The downside of this plan is that it may take up to two weeks of working time to convert the Analytica code to R. This may only be worth it, because ICT is to be converted to R anyway, and making this part now would have immediate utility for Bioher and Claih.

Decisions to be evaluated

Claih model.PNG

Figure: CLAIH assessment overview


  • Fuel for district heat production (natural gas, coal, wood, peat, oil, geothermal heat)
  • Form of district heat production (should there be more small scale district heat production?)
  • Subsidies for household heating system/energy efficiency renovations
  • Demands/subsidies for new building stock heating systems/energy efficiency
  • Demands/subsidies for building air filters


  • Household heating system renovations
  • Building energy efficiency renovations

Building stock development

Claih model building stock.PNG

Figure: Building stock development modelling

Building heat consumption

Claih model heat consumption.PNG

Figure: Building heat consumption modelling


Exposure and exposure-response functions


Claih model indoor pm.PNG

Figure: Modelling of indoor air PM2.5 concentrations from domestic wood combustion

Outdoor air concentration

Indoor air concentration

Personal exposure


Indoor dampness and mold

Indoor radon


Health impacts

ICT model.PNG

Figure: Health impact modelling

Health impact indicators

Calculated for all exposures:

  • Attributable mortality and morbidity
  • Loss of disability adjusted life years (DALY)
    • Years of life lost due to mortality (YLL)
    • Years of life lost due to morbidity (YLD)
  • Loss of life-expectancy

Background information needs




  • Costs from CO2 emissions
  • Costs to citizens


  • Cost-effictiveness analysis
  • Cost-benefit analysis
  • Value-of-information analysis

See also