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1. Building assessment

Building assessment give information about the condition of the building, need for renovation, and anticipated cost.  Major repairs and renovation foreseen within the next five to ten years, as well as need for more in-depth building inspections are typically included in the building assessment report. 

Experts of structural engineering and heating, plumbing, ventilation, and electrical installation are needed for performing a completed building assessment. It is usually recommended that first assessment should be performed when age of the building is about 10 years. After that, the assessment should be updated every five to ten years. Energy audits and related assessments could be performed at the same time.

The building assessment is commonly conducted based on a building walk-through utilizing checklists and other non-destructive assessment methods. Some simple measurements can be done, but mainly it is based on a visual evaluation about the condition of the building and the need for renovation. Also building occupants may be interviewed or surveyed to collect information and perceptions about the building, which can be used to complement the assessment. There exists some common guidelines for ordering, performing, and reporting the building assessment, and in some countries, building owners may apply for financial aid to cover the cost related to the building assessment.

2. Building inspections

If the condition of some part of the building is difficult to assess, the assessor will suggest more detailed inspection. The purpose of the building inspections is to give more precise and detailed information about condition of the critical parts of the building. On the other hand, it gives information for renovation planning and for choosing appropriate renovation methods. Typical parts which could need more detailed inspection are:

•Structures or structural components, such as outer walls, balconies, rooms with a floor gully, roofs

•Plumbing system

•Electrical systems 

•Heating systems

•Ventilation systems

•Indoor environmental quality (IEQ)

 

Professional education and experience is required for performing these inspections. Also the author should have proper tools and equipment for taking and analyzing samples. 

 

The methods and procedures of the inspection vary depended on the inspection item. There are several methods and their combinations, which could be used in the inspection:

•Studying design plans and other documents

•Visual based inspection

•Structural openings and other destructive methods

•In situ measurements and tests

•Illustrations and viewing of structures and piping  

•Taking samples and analyzing them at a laboratory.

 

Following are some structural measurements which could be included in building inspections that could be also related to IEQ.

2.1 Surface temperatures

Measuring surface temperatures of the outer walls helps tracking spots with poor thermal insulation, heat / cold bridges and air leakage. Surface temperatures can be measured using thermographic camera or surface temperature meters. Surface temperature is usually presented as a thermal index (TI), which takes into account outdoor and average indoor temperature at the measurement point. According to the Finnish guide for the occupational health (Asumisterveysohje 2003), good level is TI ≥ 65 and adequate level is TI ≥ 61.

2.2 Airtightness

Airtightness of the building envelope is usually defined by so-called blower door test. The special equipment (blower door) is installed on the one door and all other openings (doors, windows, chimneys, ventilation vents) are sealed. The equipment creates 50 Pascal under or over pressure into whole building and measures leaking air, as well as calculates the airtightness value, n50 or air leakage value q50.  If another value than q50=4 m3/h m2 is used for calculating the E-value of the building, the airtightness should be measured. It is quite difficult and laborious work to measure the airtightness of a whole apartment building, while all openings in all apartments should be sealed. It is also possible to measure airtightness of one apartment, but it is not very reliable, because there are some air leakages through the walls between different apartments. 

2.3 Air change rate

Measuring air change rate is a basic part of an inspection of ventilation systems. The inspection includes visual inspection of the condition and cleanness of the air channels, vents, and air supply units. If the building is equipped mechanical ventilation, the air exchange rate could be assessed by measuring air flows from the exhaust air vents. It is quite difficult to assess the air change rate if the building has natural ventilation. In such case, air change rate can be assessed by using so-called tracer gas method. It is commonly agreed upon that air change of an apartment should be at least 0.5 m3/h in all the rooms (air change rate 0.5 l/h).

2.4 Pressure difference

Balancing of the ventilation is the most important item concerning pressure difference between outdoor and indoor air. Also the temperature difference between the indoor and outdoor and the outdoor conditions (wind) effect on the pressure difference.  

If there is high over pressure between the outdoor and indoor, moist indoor air could transfer into the structures and condensate. On the contrary, if there is a high under pressure, all the impurities of the structures and surroundings (e.g. radon from the soil underneath the building) could be sucked into the indoor air. Table below shows the allowable pressure differences in the different type of ventilation systems according to the Finnish guidelines.

 

Ventilation system Pressure difference                                 Notes               
Natural

0...-5 Pa against outdoor

 

0 Pa against staircase

Pressure differences vary a lot enclosed to weather
Mechanical exhaust

-5...-20 Pa against outdoor

 

0...-5 Pa against staircase

Pressure differences vary a lot enclosed to weather
Mechanical inlet and exhaust

0...-2 Pa against outdoor

 

0 Pa against staircase

Pressure differences vary a lot enclosed to weather