Heating with a Minisplit Heat Pump

first_imgThirty-five years ago, when I first got involved with energy efficiency and renewable energy, the mere suggestion that one might heat with electricity would be scoffed at by those of us seeking alternatives to fossil fuels.Amory Lovins, founder of the Rocky Mountain Institute, likened using electricity for heating to “cutting butter with a chainsaw.” Electricity is a high-grade form of energy; it doesn’t make sense to use it for a low-grade need like heating, he argued. It made much more sense, we all agreed, to produce that 75-degree warmth with solar collectors or passive-solar design.So, it’s a big surprise that I’m now arguing that electricity can be the smartest way to heat a house. And that’s what we’re doing in the farmhouse we’re rebuilding in Dummerston. I should note, here, that all of our electricity is being supplied by a solar array on our barn. Our Mitsubishi heat pumpWe installed a state-of-the-art Mitsubishi M-Series FE18NA heat pump that is rated at 21,600 Btu/hour for heating and 18,000 Btu/hour (1 1/2 tons) for cooling. Marc Rosenbaum, P.E. ran heat load calculations showing peak heating demand (assuming –5°F outside temperature) about 23,000 Btu/hour, assuming the air leakage we measured several months ago, before the house envelope was completed. If the air leakage ends up being cut in half from that measured level, the design heat load would drop to a little over 19,000 Btu/hour.We think the FE18NA model will work fine for nearly all conditions, but we are also installing a small wood stove — the smallest model made by Jøtul — for use on exceptionally cold nights.The indoor unit of our heat pump is about 43 inches long by 13 inches tall by 9 3/8 inches deep. It is installed high on a wall extending in from the west wall of the house, next to an open stairway to the second floor; it is controlled with a hand-held remote. The outdoor unit, installed just off a screen porch on the west side of the house, is 35 inches tall by 33 inches wide by 13 inches deep. It is located under an overhang and held off the ground by granite blocking.ARC Mechanical from Keene, New Hampshire, did a great job with installation, and the system has now been turned on. We won’t move in until December, but it’s nice to know we have heat. Point-source heating and coolingDuctless minisplit heat pumps are ideally suited for compact, highly energy-efficient homes. Our house has R-values greater than R-40 in the walls and R-50 in the roof, plus very tight construction. We also have a heat-recovery ventilator (HRV) for fresh air. In tight, superinsulated homes, a single space heater (point-source heating system) can work very well, because with all the insulation fairly uniform temperatures are maintained throughout the house.With our 1,700 square-foot house, the two upstairs bedrooms may stay a little cooler than the downstairs, but we like a cooler bedroom. In a larger house or one that isn’t as well insulated, several ductless minisplit heat pumps or a ducted heat pump option might be required. Alex is founder of BuildingGreen, Inc. and executive editor of Environmental Building News. In 2012 he founded the Resilient Design Institute. To keep up with Alex’s latest articles and musings, you can sign up for his Twitter feed. Installing a Ductless Minisplit SystemHeating a Tight, Well-Insulated House Will Minisplits Replace Forced-Air Heating and Cooling Systems?Air-Source or Ground-Source Heat Pump?Product Guide: Mitsubishi Mr. Slim Ductless MinisplitGBA Encyclopedia: Ductless Minisplit Heat Pumps Heat pump basicsHeating with electricity makes sense if instead of using that electricity directly to produce heat — through electric-resistance strip heaters — we use a device called a heat pump. For every one unit of energy consumed (as electricity), two to three units of energy (as heat) are delivered. This makes heat pumps significantly less expensive to operate than oil or propane heating systems in terms of dollars per delivered unit of heat. RELATED ARTICLES Heat pumps use electricity in a seemingly magic way, to move heat from one place to another and upgrade the temperature of that heat in the process. Heat pumps seem like magic because they can extract heat from a place that’s cold — like Vermont’s outdoor air in January, or underground — and deliver it to a place that’s a lot warmer.Very significantly, heat pumps can be switched from heating mode to cooling mode with a flip of a switch. In the cooling mode, they work just like a standard air conditioner.Ground-source or geothermal heat pumps rely on the ground (or groundwater) as the heat source in the heating mode (and as the heat sink for cooling), while air-source heat pumps use the outside air as the heat source and heat sink. Because temperatures underground are much warmer than the outside air in winter, the efficiency of ground-source heat pumps is typically higher than that of air-source heat pumps.But ground-source heat pumps are really expensive. Friends in southern Vermont have spent $35,000 — or even more — to install residential-sized ground-source heat pumps. The cost is so high because of the cost of trenching or drilling wells.By contrast, air-source heat pumps are much simpler and far less expensive. The most common types today — and what we installed at Leonard Farm — are referred to as ductless minisplit heat pumps. There is an outdoor compressor (a box about 3 feet on a side and 1 foot deep), an indoor unit (evaporator with blower) that mounts on an interior wall, and copper tubing that carries refrigerant between the two.The typical installed cost of a ductless minisplit system is $3,000 to $5,000, though many variables affect the cost.These air-source heat pumps are viable today, even in cold climates, because of dramatic improvements in the past few decades. Much of this innovation has been driven by Japanese companies, including Mitsubishi, Daikin, Fujitsu, and Sanyo (now part of Panasonic).Several decades ago, air-source heat pumps only made sense in climates that rarely dropped below 30°F in the winter; today some of these systems, including ours, will function well at temperatures below zero degrees F.last_img read more

Understanding the Brahmaputra and the annual flooding in Assam

first_imgSand is being dug from the river Brahmaputra due to massive siltation in the water ways in the outskirts of Guwahati on November 25, 2015. Gulzarilal Nanda, Union Planning Minister, visit a rapid survey of flood and erosion-affected areas of Assam on August 22, 1954. Photo shows the Union Minister (third from right) looking at the swirling Brahmaputra at Palasbari about 14 miles from Guwahati.  | Photo Credit: The Hindu Archives The permanent destruction of wetlands in the State has also been contributing to the deluge. File The massive earthquake that ravaged Assam on Independence Day that year not only claimed over 1,000 lives, but also changed the course of the mighty Brahmaputra. The riverbed rose as the mountains shook, and what had been a stable course became a constantly shifting one eroding the banks.This especially increased the amount of silt carried by the river and its tributaries. The silt was deposited on the banks downstream, and on the riverbed. Due to this heavy deposition, the river “frequently changes its course with the main channel flowing into multiple channels” hitting the river bank causing further erosion, a study published in 2014 by the Civil Engineering Department, Royal Group of Institutions explains.The riverbed area of the Brahmaputra has increased by more than 50 per cent through erosion since the quake. According to a report on climate change published by the government of Assam in September 2015, erosion has destroyed more than 3,800 square kilometres of farmland, which is nearly half the size of Sikkim, since 1954. Due to erosion, the riverbed area has expanded from around 3,870 sq.km. estimated between 1916 and 1928 to 6,080 sq.km. in 2006. Based on the civil engineering report, between 1954 and 2008 about 4,27,000 hectares has been eroded at the rate of 8,000 hectares per year.  Controlling the floodsOne of the main methods used in the State to control floods is embankments, but almost every year the Brahmaputra and the Barak breach their banks, inundating agricultural land and houses. “The most recent embankments are 25 years old,” says Himanshu Thakkar, coordinator of the South Asia Network on Dams, Rivers and People. “Checking embankments before monsoon should be done as we never know where it will be breached. When the flow is extreme, erosion capacity is greater,” he adds.In August this year, the State government announced that as many as five dredgers will be used to deepen the Brahmaputra, and the harvested silt will be used to construct the 725-km Brahmaputra Expressway along both banks of the river. In an earlier report, the Chief Minister Sarbananda Sonowal told The Hindu: “We believe it will not only improve the water-carrying capacity of the Brahmaputra, but also make the river navigable for bigger cargo ships. That used to be the case before Independence.”Sanjoy Hazarika, director of the Commonwealth Human Rights Initiative is unconvinced. He is for an engineering assessment, along with environment assessment, as dredging “might change the course of river.” Mr. Thakkar adds that the way dredging is done followed by the construction of highway on both banks will determine the changes the river will see.The Brahmaputra Board, under the Ministry of Water Resources, had suggested constructing dams in Assam and Arunachal Pradesh about 30 years ago, the Subansiri project being one of them. Subansiri was initially designed as a hydro-power and storage dam, which the board believed would help reduce the impact of floods. However, it was later transformed into just a hydroelectric project aimed at generating 2000 megawatts of electricity, which invited opposition from local people and environment scientists.There is the possibility that hydro electric projects can worsen the situation. “Ranganadi project is a classic example of damage caused by the dam in downstream,” Mr. Thakkar points out. The dam in Arunachal Pradesh — part of a hydro-electric project — is on the Ranganadi tributary of Brahmaputra. During winter the river barely exists, but during monsoon it swells up, inundating villages. The All Assam Students’ Union in July this year demanded demolition of the Ranganadi hydro project, alleging that release of water by the North Eastern Electric Power Corp. on July 11 without prior notice affected hundreds of thousands of people in Lakhimpur and Majuli, media reported.  A similar story was told by Nishikant Deka, 80, of Gorubandha, a village about 40 km from Guwahati. He and his 12-member family had to evacuate their house in neck-deep water and take shelter at a naamghar (public prayer hall). They managed to carry some rice, and food provided once in a while by NGOs kept them going. The head of the house described how almost every year the family has to reconstruct the bamboo home that floodwaters destroy.The government of Assam estimates that 2,753 human lives have been lost along with 6,73,329 cattle and the total losses due to floods and erosion amount to nearly ₹4659.472 crore. Flooding this year took the lives of 157 people and destroyed hundreds of acres of land. According to the state disaster management authorities, in the past five years, flooding has killed about 500 people. | Photo Credit: Ritu Raj Konwar The permanent destruction of wetlands in the State has also been contributing to the deluge. Assam is home to more than 3,000 wetlands and many varieties of flora and fauna. “Wetlands, locally known as beels, act as reservoirs and rejuvenating them before monsoon can help in mitigating flood in parts of the state,” said Dulal Chandra Goswami, former head of department of environmental science at Guwahati University.“Wetlands play a very significant role as natural reservoirs of water that absorb part of the flood waters from the nearby rivers through their connected channels and also from surface runoff,” Mr. Goswami explains. Most of these wetlands are in derelict condition mainly due to human-induced factors such as encroachment for agriculture or infrastructure development.“To mitigate floods, any potential practical solution should be based on an integrated, multidisciplinary basin management plan focused on water and soil conservation together with geo-environmental, eco-biological and socio-cultural integrity of the basin,” Mr. Goswami says. “The basin management approach is essential in view of the interstate as well as international character of most of the tributaries and the mainstream.”Effects of Climate ChangeCompounding the issue of an unpredictable Brahmaputra, are the effects of climate change. “Climate change will result in more frequent and severe floods, which will increase the costs of reconstruction and maintenance on state infrastructure, including roads, irrigation, water and sanitation,” says the report on climate change published by the Assam government.According to the study, by 2050, the average annual runoff of the river Brahmaputra will decline by 14 per cent. However, there is a risk of glaciers melting, leading to flash floods.As the economy of Assam is largely dependent on natural resources, what happens with agriculture and forests has direct effects on the livelihood of its people. During floods, water becomes contaminated, and climate change has a direct impact on the water resources sector by increasing the scarcity of freshwater, which is a constant problem in summer.“The predicted increase in average temperature and decrease in the number of rainy days due to climate change will further stress water resources,” the report points out.The study goes on to say that heavier rainfall replacing continuous low or normal rainfall during monsoon might lead to flash floods in low-lying areas. This will also reduce the groundwater recharge. | Photo Credit: Ritu Raj Konwar  Change in approachWhile the present approach towards flood has been immediate relief, much more need to be done before torrential rains hit the State during monsoon. The short-term measures on which flood management in the State presently depends, such as rebuilding the breached embankments, are largely inadequate.Besides, more accurate and decentralised forecasts of rain can help in improving preparedness. “Weather reports should be made available on district level and should be accessible to public,” says Mr. Thakkar of the South Asia Network on Dams, Rivers and People. “Information should be available in local languages. With the forecast in, one can calculate how much more water will flow downstream, thereby alerting people in advance to evacuate. The nature of rivers is such that there is no way one can flood-proof whole of Assam so one has to keep it mind that floods will happen.”He adds that the water flow information shared by China on the Brahmaputra with India, for which India pays a certain amount, should also be shared with the public, as this will help in understanding the river better and therefore help people better prepare for floods.As the research scholars point out, studying the river and the impact of climate change is a must to understand why the state gets flooded every year. As line in a famous Assamese song goes: “Luitar parore ami deka lora; moribole bhoi nai (We are the youths from the banks of the Luit [Brahmaputra]; we are not afraid of death),” people in the Valley seems to be living by the same spirit. The human costLalita Biswas, 30, a daily wage earner at a brick factory in Morigaon, Assam, had to leave her submerged house in a village in Morigaon in a boat provided by villagers and take shelter in an open space on a nearby hillock. She was living in a polythene tent with her husband, who also works at the brick factory, and children. Her children have suffered from colds and fevers, and her family did not receive any help from the government, she said.“We’re always neglected because we are poor,” she said when asked if she had received any help from the state authorities. Ms. Biswas wasn’t alone. About 100 people climbed the hills to escape the flood and have to rebuild their houses and lives.Also Read All you need to know about Assam floods Marooned houses in the flood affected Morigaon district of Assam. “The river was swollen the morning after the earthquake, which seemed to last for an eternity. We saw fallen trees in it, people and animals flailing, dead bodies of people and animals that were carried on the strong current.”Krishna Chawla (née Das) was 13 when a strong earthquake that lasted about eight minutes jolted Assam and adjacent areas on the evening of August 15, 1950.The Brahmaputra River, which was always “eating away at parts of the state,” looked terrifying, she recollects. “All of us students went to help build embankments the next day, and while I was passing a bag full of sand to a fellow student, I saw the river take away the house I was born in. The house collapsed, and I stood there paralysed,” said Ms. Chawla, the daughter of a forest officer in Dibrugarh. | Photo Credit: Ritu Raj Konwarlast_img read more