Natural ventilation with traditional Korean opening in contemporary house

In this study, a natural ventilation opening was designed based on the traditional Korean opening to improve indoor environment on the contemporary house. The prototype of the opening was composed of three hanji papers and two air layers to improve airflow rate, and also to recovery heat lose. The performance of the heat recovery and airflows of the prototype was measured in laboratory, and the CFD simulation was used to verify its performance in the contemporary house. The airflow rate of the prototype is exponentially increased according to the pressure differences, and it ranges from 12.6 to 39.6 m³/m² h in 3–10 Pa, pressure difference. The total amount of heat recovery ranges from 47.8 to 67.7 W/m² in the prototype, and the heat recovery rate is about 25% at 10 Pa. In the CFD simulation, the prototypes were installed at 25% of the total window areas of the model house. The outside air was totally supplied through the prototypes at 67.2 m³/h in the model house, and it is equivalent to 0.2 h⁻¹ ventilation rate. The results show that the prototype is capable of providing natural ventilation even at low wind pressure, and also that it prevent cold draft in heating period. Further analysis of the ventilation performance including the thermal force is needed to apply the prototype to the contemporary house.     

Real-life energy use in the UK: How occupancy and dwelling characteristics affect domestic electricity use

The patterns of electricity consumption were studied for 27 representative dwellings in Northern Ireland. The type of dwelling, its location, ownership and size, household appliances, attributes of the occupants including number of occupants, income, age and occupancy patterns have differing but significant impacts on electricity consumption. A clear correlation was found between average annual electricity consumption and floor area. The monthly consumption of detached houses is between 3.57 and 5.17 kWh m⁻²; semi-detached between 3.44 and 4.59 kWh m⁻² and terraced houses between 2.5 and 3.9 kWh m⁻². The average winter consumption exceeded the average summer consumption by 1.59 kWh m⁻² for detached, by 1.16 kWh m⁻² for semi-detached and by 1.78 kWh m⁻² for terraced houses. The difference in the annual demand on the grid between detached and terraced houses is between 24 and 30%. The electricity consumption per person decreases as the number of occupants increases. This is particularly significant in large dwellings but smaller numbers of occupants.     

Passive cooling for air-conditioning energy savings with new radiative low-cost coatings

Passive cooling is considered as an alternative technology to avoid unwanted heat gains, to reduce urban heat islands and to generate cooling potential for buildings (limiting air-conditioning energy). According to materials and surface treatments, the roof can represent to be a major heat gain source from opaque elements of the building fabric, heating up the outer surface and increasing heat flow by conduction. This paper presents low-cost new radiative materials (1 ∉/m²) allowing to limit heat gains during diurnal cycle for hot seasons. To evaluate the relevance of these new substrates, their reflective UV-VIS-IR behavior are studied and compared to classical roofed materials available in industrial and developing countries. A 48 m² experimental roof having different surfaces (plate steel sheets, fiber cement, terra cotta tiles and corrugated sheets) allows to determine the temperature ratio δ between uncoated and coated materials. Up to 34% surface temperature gains are obtained for white coated CS, 25% for FC and ∼18% for TCT and PSS. According to uncoated materials for a surface temperature T₀ = 60 °C, simulations showed that the low-cost white opaque reflective roofs (50 m²) presented in this study would reduce cooling energy consumption by 26-49%.     

Temperatures and heating energy in New Zealand houses from a nationally representative study—HEEP

The household energy end-use project (HEEP) has collected energy and temperature data from a randomly selected, nationally representative sample of about 400 houses throughout New Zealand. This database has been used to explore the drivers of indoor temperatures and heating energy. Initial analysis of the winter living room temperatures shows that heating type, climate and house age are the key drivers. On average, houses heated by solid fuel are the warmest, with houses heated by portable LPG and electric heaters the coldest. Over the three winter months, living rooms are below 20 °C for 83% of the time—and the living room is typically the warmest room. Central heating is in only 5% of houses. Solid fuel is the dominant heating fuel in houses. The lack of air conditioning means that summer temperatures are affected by passive influences (e.g. house design, construction). Summer temperatures are strongly influenced by the house age and the local climate—together these variables explain 69% of the variation in daytime (9 a.m. to 5 p.m.) living room temperatures. In both summer and winter newer (post-1978) houses are warmer—this is beneficial in winter, but the high temperatures in summer are potentially uncomfortable.     

Spatial distribution of air temperature as a measure of ventilation efficiency in large uninsulated cowshed

Ventilation in the building is to assure a microclimate suitable for humans and animals as well as the durability of structures. Based on the data from literature theoretical heat and moisture balancing ventilation rate calculations for uninsulated cowshed are presented. At an indoor temperature of −6.7 °C and indoor–outdoor temperature difference of 1 °C, the theoretical ventilation rate of 2300 m³/h per cow is necessary to remove the water vapour produced by the cows from the building. At a difference of 2 °C the ventilation rate of 1200 m³/h per cow and at 5 °C 530 m³/h per cow is needed. But these calculated ventilation rates are probably unrealistic. Traditional methods are unreliable for uninsulated cowsheds and instead of that an alternative method for evaluating the ventilation rate is needed.     

Hexavalent chromium in house dust — A comparison between an area with historic contamination from chromate production and background locations

In contrast to Cr^+ 3, Cr^+ 6 is carcinogenic and allergenic. Although Cr^+ 6 can occur naturally, it is thought that most soil Cr^+ 6 is anthropogenic, however, the extent of Cr^+ 6 in the background environment is unknown. Cr^+ 6-containing chromite ore processing residue (COPR) from chromate manufacture was deposited in numerous locations in Jersey City (JC), New Jersey. In the 1990's, significantly elevated concentrations of total Cr (Cr^+ 6 + Cr^+ 3) were found in house dust near COPR sites. We undertook a follow-up study to determine ongoing COPR exposure. We compared Cr^+ 6 in house dust in JC to selected background communities with no known sources of Cr^+ 6. Samples were collected from living areas, basements and window wells. Cr^+ 6 was detected in dust from all JC and background houses. In the JC homes, the mean (± SD) Cr^+ 6 concentration for all samples was 3.9 ± 7.0 μg/g (range: non-detect-90.4 μg/g), and the mean Cr^+ 6 loading was 5.8 ± 15.7 μg/m² (range: non-detect-196.4 μg/m²). In background homes, the mean Cr^+ 6 concentrations of all samples was 4.6 ± 7.8 μg/g, (range, 0.05-56.6 μg/g). The mean loading was 10.0 ± 27.9 μg/m² (range, 0.22-169.3 μg/m²). There was no significant difference between Cr^+ 6 dust concentrations in Jersey City and background locations. Stratification by sample location within houses and sampling method gave similar results. Samples exceeding 20 μg/g were obtained only from single wood surfaces in different homes. Lower concentrations in window well samples suggests transport from outside is not the major source of indoor Cr^+ 6. Landscaping and groundcover may influence indoor Cr^+ 6. There appears to be a widespread low level background of Cr^+ 6 that is not elevated in Jersey City homes despite its historic COPR contamination. It is possible that house dust, in general, is a source of Cr^+ 6 exposure with potential implications for persistence of chromium allergic contact dermatitis.     

Performance assessment of low-energy buildings in central Argentina

This paper summarizes the results obtained from the energy and thermal performance assessment of residential and non-residential low-energy buildings that were designed to minimize fossil energy use. They are located in the province of La Pampa, central Argentina, in a temperate continental climate that shows extreme hot and cold records during the summer and winter seasons, respectively. The common applied technologies for saving energy were passive solar heating, natural ventilation for cooling and daylighting. The glazing area in the principal functional spaces facing to the North oscillates between 11 and 17% of the building useful areas. All the studied buildings are massive, with the exception of an auditorium that was designed with a lightweight insulated technology. The mean thermal transmittance of the envelope is 0.45 W/(m² K). Double glazing and hermetic carpentry were used to reduce thermal losses (U-value = 2.8 W/(m² K)). The volumetric heat loss coefficient (G-value) oscillates between 0.90 and 1.00 W/(m³ K). During the design and thermal simulation convective-radiative heat transfer coefficients were estimated through a dimensional equation (h = 5.7 + 3.8 ws, wind speed). On internal surfaces, convective-radiative heat transfer coefficients of 8 and 6 W/(m² °C) (for surfaces with and without solar gain, respectively) were applied. The monitoring process provided information on the energy and thermal behaviour under use and non-use conditions. The measured value of energy consumption was similar to the expected value that was used during the pre-design stage. Building technologies work well during the winter season, allowing 50–80% of energy savings. However, overheating is still an unresolved problem during the summer. Interviews with occupants revealed that they need both, information about functional details, and good-practice guidance to manage thermal issues of the building. In most cases, the annual consumption of energy was lower than those established by the Low Energy Housing German Standards and the Minirgie Switzerland Certificate. Despite their relative cost increase during the last years, the use of insulation technology and the application of passive solar devices involved an extra cost of only 3% in our works. Provided the expected depletion of natural gas production in the coming decade, the importance of applying energy-efficiency guidelines will increase very soon in Argentina in order to match the requirements of a new national energy matrix.     

Assessment of climate change impact on residential building heating and cooling energy requirement in Australia

This study investigated the potential impact of climate change on the heating and cooling (H/C) energy requirements of residential houses in five regional climates varying from cold to hot humid in Australia. Nine General Circulation Models (GCMs) under three carbon emission scenarios were applied to project the local climate. It was found that significant climate change impact on H/C energy requirements may occur within the lifespan of existing housing stock. The total H/C energy requirement of newly constructed 5 star houses is projected to vary significantly in the range of −26% to 101% by 2050 and −48% to 350% by 2100 given the A1B, A1FI and 550 ppm stabilisation emission scenarios, dependent on the existing regional climate. In terms of percentage change, houses in an H/C balanced temperate climate such as Sydney is found to be the most sensitive to climate change, potentially posing more pressures on the capacity of local energy supply. It was also found that energy efficient or high star rating houses may experience less absolute changes in energy requirement. However, they appear to experience higher percentage changes in the total H/C energy requirement. Especially in the regions with an H/C balanced temperate climate such as Sydney, the increase in the total H/C energy requirement is projected up to 120% and 530% for a 7 star house when the global temperature increases 2 °C and 5 °C respectively. The high sensitivity to global warming may need to be considered in the planning of future energy requirement for energy efficient buildings.     

Solar integrated energy system for a green building

Shanghai is characteristic of subtropical monsoonal climate with the mean annual temperature of 17.6 °C, and receives annual total radiation above 4470 MJ/m² with approximately 2000 h of sunshine. A solar energy system capable of heating, cooling, natural ventilation and hot water supply has been built in Shanghai Research Institute of Building Science. The system mainly contains 150 m² solar collector arrays, two adsorption chillers, floor radiation heating pipes, finned tube heat exchangers and a hot water storage tank of 2.5 m³ in volume. It is used for heating in winter, cooling in summer, natural ventilation in spring and autumn, hot water supply in all the year for 460 m² building area. The whole system is controlled by an industrial control computer and operates automatically. Under typical weather condition of Shanghai, it is found that the average heating capacity is up to 25.04 kW in winter, the average refrigerating output reaches 15.31 kW in summer and the solar-enhanced natural ventilation air flow rate doubles in transitional seasons. The experimental investigation validated the practical effective operation of the adsorption cooling-based air-conditioning system. After 1-year operation, it is confirmed that the solar system contributes 70% total energy of the involved space for the weather conditions of Shanghai.     

Review of thermal comfort design based on PMV/PPD in cabins of Korean maritime patrol vessels

This study has focused on the evaluation of the optimal temperature in each cabin of the Korean maritime patrol vessels. We aptly modified the inland indoor items and criteria of clothing and activities, and then investigated the human factors in the cabins of Korean maritime patrol vessels. The total thermal resistance of clothing in the wheelhouse was 0.097, 0.079, 0.096, and 0.130 m² °C/W and that for the accommodation areas was 0.067, 0.059, 0.084, and 0.101 m² °C/W in spring, summer, fall, and winter, respectively. The metabolic rate was 228.04 W/m² in the training room and above 100 W/m² in the engine room and auxiliary machine room. In the wheelhouse and accommodation, the metabolic rate was 78.14 and 44.45 W/m², respectively. Based on human factors, the optimum temperature was 23 °C in the wheelhouse and 29 °C in the accommodation. Therefore, 6 °C of energy can be saved in case of PMV/PPD-based air conditioning.     

Evaluating a low exergy heating system from the power plant through the heat pump to the building envelope

This study deals with an exergetic analysis and assessment of a low exergy heating system from the power plant through the ground-source heat pump to the building envelope. The methodology used is based on a pre-design analysis tool, which has been produced during ongoing work for the International Energy Agency (IEA) formed within the Energy Conservation in Buildings and Community Systems Programme (ECBCSP) Annex 37 to increase the understanding of exergy flows in buildings and to be able to find possibilities for further improvements in energy utilization in buildings. The analysis is applied to a room with a volume of 105 m³ and a net floor area of 35 m² as an application place, while indoor and exterior air temperatures are 20 °C and −15 °C, respectively. The heat pump system used for heat production with a maximum supply temperature of 55 °C was designed, constructed and tested in Aksaray University, Aksaray, Turkey. In this context, energy and exergy flows were investigated, while exergy destructions in the overall system were quantified and illustrated. Total exergy input of the system was found to be 7.93 kW and the largest exergy destruction occurred in the primary energy transformation at 5.31 kW.     

Energy and emergy based cost–benefit evaluation of building envelopes relative to geographical location and climate

This paper presents an environmental evaluation of building envelopes, made of three different technologies: a traditional air-cavity wall, a plus-insulated wall (with an external cork covering), and a ventilated wall (with external brick panels fixed on extruded frames). An environmental accounting method, namely Emergy Evaluation (EE), was performed for assessing environmental resource use (energy and material flows), both directly and indirectly, for the construction of a façade (1000 m²). Then, energy use during the building lifetime was assessed as a constant inflow to the building depending on the thermal skills of building envelopes, besides thermal efficiency of air-conditioning system. In particular, this energy inflow is needed for maintaining constant indoor climate conditions (18 °C) and has to balance heat dissipation through envelopes (heat loss in winter and heat gain in summer). Outcomes were compared with an Energy Analysis (EA) based on an embodied energy accounting. Finally, costs for manufacturing walls (with enhanced performance) and benefits (energy saving) were compared in a unique balance, through both EA and EE. Moreover, outcomes were obtained for three scenarios corresponding to three geographic locations (Berlin in northern Europe, Barcelona on the Mediterranean coast and Palermo in the south of Italy). Results highlighted that performances of building envelopes depend on technologies relative to external climate conditions. Different environmental accounting methods, such as EE and EA, provided outcomes with some difference that are not contradictory to each other but complementary.     

Thermal characteristics of a double-glazed external wall system with roll screen in cooling season

A double-skin system (double-glazed external wall) is an effective passive system that can be used to decrease solar heat gain into buildings. Detailed information on the thermal distribution of double-skin facades is necessary to design better systems that can provide thermal comfort and conserve energy. In this study, the three-dimensional thermal characteristics of double-skin facades that had the ventilation opening installed partially and were screened partially by the adjacent buildings were investigated by field measurements. To that end, field measurements were carried out on the double-skin exterior wall (9.4 m high and 27.0 m wide) installed in an atrium located in the west of an existing building during cooling period for typical summer conditions. Maximum air change rate of natural ventilation through the bottom opening up to the top opening is about 20–25 [1/h], the reduction ratio of total solar heat gain compared with those of non-natural ventilation is about 25%. The exhaust solar heat gain is about 100 W/m² per inner glass surface area of the double-skin facades. Air temperature distribution of air space in the double skin was ranged from 30 °C to 44 °C, and heat gain difference ranged from 50 W/m² to 130 W/m². The influence of the ventilation openings and the shade conditions on temperature distribution of double skin is found to be significant and the double-skin system was verified to reduce the cooling loads effectively.     

Eawag Forum Chriesbach—Simulation and measurement of energy performance and comfort in a sustainable office building

The Eawag's new headquarters “Forum Chriesbach” is an exemplary illustration of a ‘sustainable’ construction design for office buildings. With a unique combination of architectural and technical elements the building reaches a very low 88 kWh/m² overall primary energy consumption, which is significantly lower than the Swiss Passive House standard, Minergie-P. A monitoring and evaluation project shows that the building is heated mainly by using the sun and internal heat gains from lighting, electrical appliances and occupants, resulting in an extremely low space heating demand. Cooling is provided by natural night time ventilation and the earth-coupled air intake, which pre-cools supply air and provides free cooling for computer servers. However, values for embodied energy and electricity consumption remain significant, even with partial on-site electricity production using photovoltaics. TRNSYS computer simulations show the contributions of individual building services to the overall energy balance and indicate that the building is resilient towards changes in parameters such as climate or occupancy density. Measurements confirm comfortable room temperatures below 26 °C, even during an extremely hot summer period, and 20-23 °C in the winter season. An economic analysis reveals additional costs of only 5% compared to a conventionally constructed building and a payback-time of 13 years.     

Building leakage,infiltration, and energy performance analyses for Finnish detached houses

This study focuses on the relation between the airtightness of a building envelope, infiltration, and energy use of a typical modern Finnish detached house in the cold climate of Finland. The study is conducted with an empirically tested dynamic IDA-ICE simulation model of a detached house. The effect of several factors, such as Finnish climate and wind conditions, balance of ventilation system and leakage distribution, on infiltration was studied and a simple adapted model for the rough estimation of annual infiltration in Finnish detached houses was determined from the numerical simulation results. The energy impact of infiltration is also studied, taking into account the infiltration heat recovery effect. According to the results, infiltration causes about 15–30% of the energy use of space heating including ventilation in the typical Finnish detached house. The average infiltration rate and heat energy use increase almost linearly with the building leakage rate n₅₀. Finland can be roughly divided into two zones based on the average infiltration rate of detached houses, for which stack-induced infiltration is typically dominant, regardless of the climate zone. The infiltration heat recovery effect is minor in the studied detached house.     

Boiling heat transfer enhancement with carbon nanotubes for refrigerants used in building air-conditioning

In this study, the effect of carbon nanotubes (CNTs) on nucleate boiling heat transfer is investigated. Two halocarbon refrigerants of R123 and R134a for building chillers were used as working fluids and 1.0 vol.% of CNTs was added to them to examine the heat transfer enhancement with CNTs. The experimental apparatus was composed of a stainless steel vessel and a 152.0 mm long plain horizontal tube of 19.0 mm outside diameter heated by a cartridge heater. All data were obtained at the pool temperature of 7 °C in the heat flux range of 10–80 kW m⁻². Test results showed that CNTs increase nucleate boiling heat transfer coefficients for these refrigerants. Especially, large enhancement up to 36.6% was observed at low heat fluxes of less than 30 kW m⁻². With increasing heat flux, however, the enhancement was suppressed due to vigorous bubble generation. Fouling on the heat transfer surface was not observed during the course of this study. Optimum dispersion of CNTs should be examined for their commercial application to enhance nucleate boiling heat transfer in building air-conditioning applications.     

Detailed energy saving performance analyses on thermal mass walls demonstrated in a zero energy house

An insulated concrete wall system¹ was used on exterior walls of a zero energy house. Its thermal functions were investigated using actual data in comparison to a conventional wood frame system. The internal wall temperature of massive systems changes more slowly than the conventional wall constructions, leading to a more stable indoor temperature. The Energy10 simulated equivalent R-value and DBMS of the mass walls under actual climate conditions are, respectively, 6.98 (m² °C)/W and 3.39. However, the simulated heating energy use was much lower for the massive walls while the cooling load was a little higher. Further investigation on the heat flux indicates that the heat actually is transferred inside all day and night, which results in a higher cooling energy consumption. A one-dimensional model further verified these analyses, and the calculated results are in good agreement with the actual data. We conclude that the thermal mass wall does have the ability to store heat during the daytime and release it back at night, but in desert climates with high 24-h ambient temperature and intense sunlight, more heat will be stored than can be transferred back outside at night. As a result, an increased cooling energy will be required.     

Coping with radon problem in a private house

In one of the 50 houses in which, during a national radon survey of 1000 homes in Slovenia, indoor radon concentrations exceeded 1000 Bq m⁻³, radon was further investigated. Except in the attic, elevated radon concentrations were found everywhere in the home, ranging from 0.5 to 12 kBq m⁻³. Applying ICRP 65 methodology, an annual effective dose in the range from 9 to 35 mSv was estimated for an inhabitant for different exposure scenarios. The radon problem was successfully mitigated and radon concentration reduced below 200 Bq m⁻³.     

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.     

Influence of zeolite additive on properties of autoclaved aerated concrete

In this experimental study, the effect of zeolite on the properties of autoclaved aerated concrete (AAC) was investigated. Zeolite was used as a quartzite replacement in conventional AAC mixtures. The zeolite containing AAC (ZAAC) specimens were prepared at bulk densities of 270–500 kg/m³. The specimens were examined by X-ray diffraction, X-ray fluorescence, and thermal analysis. Bulk density, compressive strength and thermal conductivity parameters were investigated. According to the results of research, the commercial AAC is mainly composed of tobermorite, quartz and anhydrite, but the specimens of ZAAC, besides tobermorite and quartz, contain unreacted anhydrite and clinoptilolite phases. XRD patterns of ZAAC obtained after treatment at 700–1000 °C show that wollastonite, gehlenite and orthoclase are the new phases formed. It was observed that application of zeolite in AAC significantly lowered the thermal conductivity of autoclaved products (0.08–0.12 kcal/m h °C) providing the compressive strength at the level of 1.22−3.34 N/mm².