Underground space planning in Helsinki

This paper gives insight into the use of underground space in Helsinki, Finland. The city has an undergroundmaster plan （UMP） for its whole municipal area, not only for certain parts of the city. Further, the decision-making history of the UMP is described step-by-step. Some examples of underground space usein other cities are also given. The focus of this paper is on the sustainability issues related to urbanunderground space use, including its contribution to an environmentally sustainable and aestheticallyacceptable landscape, anticipated structural longevity and maintaining the opportunity for urbandevelopment by future generations. Underground planning enhances overall safety and economy efficiency.The need for underground space use in city areas has grown rapidly since the 21st century; at thesame time, the necessity to control construction work has also increased. The UMP of Helsinki reservesdesignated space for public and private utilities in various underground areas of bedrock over the longterm. The plan also provides the framework for managing and controlling the city＇s underground constructionwork and allows suitable locations to be allocated for underground facilities. Tampere, the thirdmost populated city in Finland and the biggest inland city in the Nordic countries, is also a good exampleof a city that is taking steps to utilise underground resources. Oulu, the capital city of northern Finland,has also started to ＇go underground＇. An example of the possibility to combine two cities by an 80-kmsubsea tunnel is also discussed. A new fixed link would generate huge potential for the capital areasof Finland and Estonia to become a real Helsinki-Tallinn twin city.
2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.     

Engaging decision makers for an urban underground future

This paper will look into the topic of how decision makers can be engaged in the development of urban underground space. It will ask the question whether it is the decision makers we need to focus on, or if the development of urban underground space involves further stakeholders. The paper will look at the way the ITA Committee of Underground Space has worked in advocating underground space for the past 8 years. The question will also be asked where we stand 100 years on from the first advocates of underground urbanism.     

The effect of fuel area size on behavior of fires in a reduced-scale single-track railway tunnel

A set of experiments was carried out in a 1/9 reduced-scale single-track railway tunnel to investigate the effect of fuel area size on the temperature distribution and behavior of fires in a tunnel with natural ventilation. Methanol pool fires with four different fuel areas 0.6 × 0.3 m² (1 pan), 1.2 × 0.3 m² (2 pans), 2.4 × 0.3 m² (4 pans) and 3.6 × 0.3 m² (6 pans), were used in these experiments. Data were collected on temperatures, radiative heat flux and mass loss rates. The temperature distribution and smoke layer in the tunnel, along with overflow dimensions and radiant heat at the tunnel entrance were analyzed. The results show that as the fuel area enlarges, the fire gradually becomes ventilation-controlled and the ceiling temperature over the center of fire source declines. Burning at the central region of fire source is depressed due to lack of oxygen. This makes the temperature distribution along the tunnel ceiling change from a typical inverted V-shape to an M-shape. As observed in the experiments, a jet flame appeared at tunnel entrances and both the size and temperature of the flame increased with the enlargement of fuel area leading to a great threat to firefighters and evacuees in actual tunnel fires.     

Lessons learnt from Urban Underground Space use in Shanghai—From Lujiazui Business District to Hongqiao Central Business District

This paper presents a case study on Urban Underground Space (UUS) use in Shanghai, China. Shanghai is at the forefront of China’s modernization construction, and also sets an example for other cities in China in the field of UUS use. Surging from 2 million m² in the early 1990s to over 68 million m² in recent years, the amount of UUS in Shanghai has reached a scale previously unimaginable. From the process of Shanghai UUS development, we can learn either valuable experiences from cases like Hongqiao Central Business District (CBD) or, inevitably, profound lessons from Lujiazui Business District. Reviewing and comparing such cases will demonstrate the importance of planning and legal procedures to the development and utilization of UUS and can facilitate the further promotion of UUS use in Shanghai.     

Energy consumption and ventilation performance of a naturally ventilated ecological house in a cold climate

In this paper, the thermal and ventilation performance of an ecological house in Helsinki, Finland are presented. The single-family dwelling has a well-insulated, wooden frame construction with no plastic vapour retarder. The measured and simulated results show that the energy consumption of the house is low and that the outdoor ventilation rate is generally satisfactory based on the measured CO₂ concentrations. Extrapolating the measured ventilation data shows that, when the operable windows are closed, the ventilation rate is expected to be about 0.45 air-changes-per-hour (ach) in the winter and about 0.25 ach in the summer. The consumption of total primary energy and space heating energy were measured to be 30% less (162 kWh/(m² a)) and 36% less (76 kWh/(m² a)) than in typical Finnish houses, respectively. The paper also uses a numerical model to investigate the sensitivity of energy consumption to the insulation level, household electricity and domestic hot water consumption, window area, ventilation rate and heat recovery effectiveness.     

Snow heterogeneity in Luleå, Sweden

Snow water equivalent (SWE) and snow covered area (SCA) are fundamental considerations when planning for snowmelt events. Depth, density and albedo measurements are used to demonstrate the spatial variability of SWE in the city of Luleå, Sweden. Undisturbed urban snow is similar to nearby rural snow (albedo 0.5–0.6, density 200–300 kg m⁻³) whereas ploughed snow piles have a wide range of characteristics (albedo < 0.3–0.5, density 250–700 kg m⁻³). Snow piles are located on permeable surfaces in suburbs and impervious surfaces where landuse is intense. Snowmelt runoff simulated assuming first a homogenous then a heterogeneous snowpack shows that the presence of piles can reduce the maximum volume of melt and extend the melt period.     

Numerical simulation of air ventilation in super-large underground developments

Recent advancements in engineering technology have enabled the construction of super-large underground engineering projects in China. Currently, the ventilation requirements and standards of normal-size underground spaces are used for super-large underground excavating engineering projects in China. For example, the minimum air velocity of 0.15 m/s is the standard velocity for normal-size underground spaces; however, this value is also used as the required air velocity for diluting underground contaminants in super-large underground developments. This paper aims to examine the minimum ventilation requirements for super-large underground developments (S > 100 m²). A three-dimensional computational domain representing a full-scale underground space has been developed. The pertinent parameters such as dust concentration, smoke density, oxygen concentration and air temperature have been simulated. The results show that at some specific underground conditions, the ventilation air velocity of 0.15 m/s is sufficient to control the dust level, provide required oxygen concentration and maintain the air temperature at acceptable levels during development; however, it is not sufficient to bring the CO concentration below an acceptable safe limit. This must be considered by the ventilation system designers of super-large underground developments.     

Energy-efficient terrace houses in Sweden: Simulations and measurements

Reducing energy use in buildings is essential to decrease the environmental impact. Outside Gothenburg in Sweden, 20 terrace houses were built according to the passive house standard and completed in 2001. The goal was to show that it is possible to build passive houses in a Scandinavian climate with very low energy use and to normal costs. The houses are the result of a project including research, design, construction, monitoring and evaluation. The passive house standard means that the space heating peak load should not exceed 10 W/m² living area in order to use supply air heating. This requires low transmission and ventilation losses and the building envelope is therefore highly insulated and very airtight. A mechanical ventilation system with approximately 80% heat recovery is used. The electric resistance heating in the supply air is 900 W per living unit. Solar collectors on the roof provide 40% of the energy needed for the domestic hot water. The monitored delivered energy demand is 68 kWh/m² a. Energy simulations show that main differences between predicted and monitored energy performance concern the household electricity and the space heating demand. Total delivered energy is approximately 40% compared with normal standard in Sweden.     

Mix proportion of high-strength,roller-compacted,latex-modified rapid-set concrete for rapid road repair

In this study, we optimized a blend of high-strength, roller-compacted, latex-modified rapid-set concrete (RCLMC) that can be re-opened to traffic after 4 h. To this end, we tested several variables in laboratory experiments, including hardening acceleration agents, cement type, latex addition, and CSA admixture ratios. The target compressive strength was 21 MPa after 4 h. A mixture of Type III cement to CSA admixture at 235:165 kg/m³ (400 kg/m³ total binder) and 23.5 kg/m³ latex (10% of the cement weight) achieved the target compressive strength and was the most economically efficient.     

Modelling sheltering effects of trees on reducing space heating in office buildings in a windy city

Using statistical weather analysis, computational fluid dynamics and thermal dynamic simulation, a systematic method was developed to assess quantitatively the effects of a shelterbelt on space heating, particularly with regard to the energy consumption and CO₂ emission. It was then applied to estimate the heating loads of two typical office buildings in a windy city located at 57.2North, with and without a shelterbelt. Firstly, the statistical analysis of weather data was carried out to identify the prevailing wind direction during a typical winter heating season in the location. It was to ensure the windbreak planted rightly to maximise its sheltering benefits for the buildings in its leeward. This analysis, which revealed the main weather features in the location, would help to better comprehend the results of the thermal modelling and gain insight of how the load responses to the climate. In the second part, CFD modelling predicted wind reduction due to the shelterbelt under various wind directions. The predicted data were then used to prepare two sets of weather data, the original weather file and the revised one, in which the wind data had taken into account the reduction effect of the windbreak. The third part was a dynamic thermal modelling study where two types of office buildings were selected as the representative offices in Edinburgh for the assessment of sheltering effect on energy saving and CO₂ reduction. The predicted savings over a heating season due to the shelterbelt were in a range of 16–42% and the actual values in space heating were about 2.2 kWh m⁻² for new office buildings and 14.5 kWh m⁻² for offices converted from conventional houses without insulation improvement. These significant savings were due to the local weather that is typically known as long windy winter with many cloudy days.     

Risk analysis of LPG (liquefied petroleum gas) vehicles in enclosed car parks

A risk analysis is presented for an enclosed 30×30 m car park in which LPG (liquefied petroleum gas) vehicles are allowed to park. An event tree analysis is used to define 26 different incident scenarios and their probabilities. FLACS, a specialised CFD program, is used to calculate the formation of a flammable vapour cloud and its dilution by means of the ventilation system as well as the overpressures generated in a vapour cloud explosion. Existing empirical methods are used to calculate the overpressures generated by a BLEVE and the heat radiated by a fire ball and a jet fire. The simulations have shown that a release from a 70 l LPG fuel tank can lead to vapour clouds of up to 200 m³ that fill the entire height of the car park, while the explosion simulations have shown that such vapour clouds can lead to overpressures above 30 kPa in the entire car park. The ventilation simulations have shown that high flow rates of approximately 0.060 m³/s per m² of car park floor area are necessary to rapidly dilute these large vapour clouds.     

Evaluation of indoor environmental quality conditions in elementary schools׳ classrooms in the United Arab Emirates

This study presents findings of indoor environmental quality (IEQ) investigations conducted in elementary schools׳ classrooms in the United Arab Emirates (UAE). Average TVOC, CO₂, O₃, CO, and particle concentrations measured in the classrooms were 815 µg/m³, 1605 ppm, 0.05 ppm, 1.16 ppm, and 1730 µg/m³, respectively. Whereas, local authority known as Dubai Municipality recommended 300 µg/m³, 800 ppm, 0.06 ppm, 9 ppm, and 150–300 µg/m³ for TVOC, CO₂, O₃, CO, and particle, respectively. Dubai Municipality recommended temperature and relative humidity (RH) levels of 22.5 °C to 25.5 °C and 30%–60%, respectively. Average temperature and RH levels measured in the classrooms were 24.5 °C and 40.4%, respectively. Average sound level in the classrooms was 24 dB greater than recommended sound level limit of 35 dB. Six (6) classrooms had average lux levels in the range of 400–800 lux. Two (2) classrooms had average lux levels in the range of 100–200 lux. The remaining classrooms had lux levels around the recommended 300 lux. High occupancy density was observed in majority of the studied classrooms. Observations during walkthrough investigations could be used to explain measured IEQ data. Poor IEQ conditions in the studied classrooms highlight the need for further research investigation to understand how poor classrooms׳ IEQ condition could influence students׳ health, comfort, attendance rate, and academic performance.     

Small power equipment loads in UK office environments

This paper presents figures for the small power equipment loads encountered by the Welsh School of Architecture in UK offices while undertaking a programme of research and monitoring into the energy efficiency of air-conditioning systems in use. The findings are based on surveys undertaken in 30 air-conditioned offices between April 2000 and October 2002. Peak small power equipment loads were calculated using the CIBSE nameplate-ratio method. The results show that the small power loads averaged 17.5 W/m² with a range between 6 and 34 W/m² of treated floor area. When normalised for occupancy the calculated peak small power equipment loads averaged 158 W per person, with a range between 124 and 229 W per person. Current industry guidance could lead to the overestimation of small power equipment loads by as much as 650%, ultimately resulting in increased capital and running costs of air-conditioning plant and reduced thermal comfort. A more accurate method of estimating peak small power equipment loads in UK office buildings is suggested based on occupant density.     

Study of surface subsidence above an underground opening using a trap door apparatus

Physical model simulations have been performed to determine the effects of underground opening configurations on surface subsidence under super-critical conditions. This paper indicates the importance of the main factors that control the extent of subsidence produced on the surface and determines the effects of geometry of underground openings on the angle of draw, the maximum subsidence and the volume of the subsidence trough. A trap door apparatus with the test area of 95 × 95 cm² has been fabricated to perform the scaled-down simulations of surface subsidence. Gravel is used to represent the overburden in order to exhibit a cohesionless frictional behavior. In plan view the excavation dimensions are sufficient to induce maximum possible subsidence. The findings can be used to evaluate the subsidence profile for tunnels and caverns in soft ground. The results show that the angle of draw and the maximum subsidence are controlled by the width (W), length (L), height (H) and depth (Z) of the underground openings. The angle of draw and maximum subsidence increase with increasing L/W ratio and tends to approach a limit when L/W equals 3. For the same L/W ratio and H/W ratio, increasing the Z/W ratio reduces the angle of draw and maximum subsidence. The volume of the subsidence trough increases with increasing H/W ratio and L/W ratio. The width of the subsidence trough can be represented by sets of empirical relations. The relation between opening depth and subsidence trough developed by Rankin (for cohesionless soils) is in good agreement with most physical model results for deep openings (Z/W = 2–4), while for Z/W = 1, the predicted trough width is less than the physical model simulation. The volume of the subsidence trough is largest for Z/W = 2.5 and for H/W = 0.6, and is about 60% of volume of the underlying opening.     

Development of electrochromic evacuated advanced glazing

Electrochromic evacuated advanced glazing has been developed, combining optimum dynamic control of the solar radiation penetrating into buildings with a high degree of thermal insulation. This was achieved by the optimisation of the electrochromic device materials (electrochromic, ion storage, protective layers, transparent conductors and polymer electrolytes) and by the refinement of a sealing method for evacuated glazing. Electrochromic evacuated glazing prototypes with dimensions up to 40 cm × 40 cm have been fabricated using vacuum techniques and chemical methods. The prototypes exhibit excellent optical and thermal performance, with a contrast ratio up to 1:32 (visible dynamic transmittance range T_lum,bleached = 63% and T_lum,colored = 2%), coloration efficiency up to 92 cm²/C and mid-pane U-values as low as 0.86 W m⁻² K⁻¹. Their durability in relation to real working environmental conditions has been assessed through indoor and outdoor testing. Such a glazing can be used in building applications to improve occupant thermal comfort, contribute to a reduction in space heating and cooling loads and allow for increased areas of fenestration thereby reducing artificial lighting loads. These factors reduce the energy demand for the building and therefore contribute to the reduction of carbon dioxide emissions.     

Safe velocity of on-fire train running in the tunnel

The safety of a running train on fire in a tunnel is a key issue for rescue operations, and the train velocity is mainly related to its safety. In this study, the relationship between the wind velocity and heat release rate (HRR), temperature field around the train, and flame/smoke pervasion rule were investigated under the conditions of variable train velocity, fire location, and fire source location. Beijing Metro was considered as a typical example, in which the safe velocity was estimated to be ∼41.83 km h⁻¹. Assuming the occurrence of fire at the center of the train, the numerical simulations of the flow field using the sliding grid of CFD were performed for a full-scale tunnel under different HRRs. When the fire source reached to the target section, the velocities of all the monitoring points rapidly increased. The velocities increased as the train tail arrived at the target section. The velocities at the measuring points increased with the increase in height, excluding the value of the position with a distance of 0.025 m from the tunnel ceiling. The average temperature and concentration of smoke in the annular space between the train and tunnel ceiling had the minimum values when the running train on fire moved with a speed of 45 km h⁻¹. Thus, the safe velocity of a subway train on fire should be managed between 41.83 km h⁻¹ and 45 km h⁻¹.     

Drip sealing of tunnels in hard rock: A new concept for the design and evaluation of permeation grouting

This paper presents a new pre-excavation grouting concept to prevent dripping and reduce the inflow into a railway tunnel. For this purpose, the tunnel’s roof was drip-sealed using colloidal silica and the walls and invert of the tunnel were grouted with cement. The grouting design process followed a structured approach with pre-investigations of core-drilled boreholes providing parameters for the layout. Water pressure tests and pressure volume time recordings were used for the evaluation. Results showed that the design was successful: the total transmissivity was reduced from 4.9 × 10^?08 m²/s to the measurement limit (1.6 × 10^?08 m²/s), and the dripping was reduced to eight spots from the roof. Improved rock characterisation showed that the grout hole separation was within the transmissivity correlation length and that grouting efficiency depends to a large extent on the dimensionality of the flow system of the rock mass.     

Monitoring the energy-use effects of cool roofs on California commercial buildings

Solar-reflective roofs stay cooler in the sun than solar-absorptive roofs. Such “cool” roofs achieve lower surface temperatures that reduce heat conduction into the building and the building's cooling load. We monitored the effects of cool roofs on energy use and environmental parameters in six California buildings at three different sites: a retail store in Sacramento; an elementary school in San Marcos (near San Diego); and a four-building cold storage facility in Reedley (near Fresno). The latter included a cold storage building, a conditioning and fruit-palletizing area, a conditioned packing area, and two unconditioned packing areas.Results showed that installing a cool roof reduced the daily peak roof surface temperature of each building by 33–42 K. In the retail store building in Sacramento, for the monitored period of 8 August–30 September 2002, the estimated savings in average air conditioning energy use was about 72 Wh/m²/day (52%). On hot days when the afternoon temperature exceeded 38 °C, the measured savings in average peak demand for peak hours (noon–5 p.m.) was about 10 W/m² of conditioned area. In the school building in San Marcos, for the monitored period of 8 July–20 August 2002, the estimated savings in average air conditioning energy use was about 42–48 Wh/m²/day (17–18%). On hot days, when the afternoon temperature exceeded 32 °C, the measured savings in average peak demand for hours 10 a.m.–4 p.m. was about 5 W/m² of conditioned area. In the cold storage facility in Reedley, for the monitored period of 11 July–14 September 2002, and 11 July–18 August 2003, the estimated savings in average chiller energy use was about 57–81 Wh/m²/day (3–4%). On hot days when the afternoon temperature exceeded 38 °C, the measured savings in average peak-period demand (average cooling-power demand during peak demand hours, typically noon–6 p.m.) was about 5–6 W/m² of conditioned area.Using the measured data and calibrated simulations, we estimated savings for similar buildings installing cool roofs in retrofit applications for all 16 California climate zones. For similar retail stores in climate zones 2 and 4–16, installing a cool roof can save about 6–15 kWh/m²/year of conditioned area. In climate zones 2–16, estimates of average peak demand savings for hours noon–5 p.m. range from 2.9 to 5.8 W/m². For similar school buildings in climate zones 2–16, installing a cool roof can save from 3 to 6 kWh/m²/year of conditioned roof area. For all 16 climate zones estimates of average peak demand savings for hours noon–5 p.m. range from 2.6 to 3.8 W/m². In similar cold storage buildings in all 16 climate zones, installing a cool roof can save about 4.5–7.4 kWh/m²/year of conditioned roof area. In all 16 climate zones, estimates of average peak demand savings for hours noon–5 p.m. range from 3.9 to 6.6 W/m².